Tides

Surfing Mavericks and Nineteenth-Century Tide Theories

Should we slink back inside to our reliable equations and brood over the inconsistencies of nature? Never! Instead we must become outdoor wave researchers. It means being wet, salty, cold—and confused.

—Willard Bascom

The surf break at Mavericks, just south of San Francisco, springs to life only a few times a year during the largest Pacific swells. In fact, Mavericks, a tabletop reef that looms a half-mile off Pillar Point near the town of Half Moon Bay, is usually so calm that local fishing fleets sail over it without notice or bother. But when swells twenty feet or larger roll in from distant storms, the place transforms into a tempest. These conditions drive away fishing boats but beckon surfers from around the world to compete at Mavericks’s yearly big-wave contest.

The contest, slated each year between November and March, occurs whenever a North Pacific storm stirs waves large enough. The bigger the waves, the better. Event organizers spend their winters studying storm and wave models. If they see the right statistical lineup—a blend of tide, wind, and swell direction—they announce the contest, leaving only a day or two for contestants to fly in from around the world.

Storms and waves are fickle, however; there’s no guarantee that any given winter will deliver the right surf conditions. The winters of 2011 and 2012 never saw waves large enough to hold the contest. As the 2013 season opened, contestants and organizers hoped for a change.

On January 18, 2013, I received an email alert that a ferocious storm was kicking up fifty-foot waves in the Bering Sea. The storm was 1,500 miles away, but mountainous swells were already marching toward California’s coast. Wave models predicted twenty- to thirty-foot faces by the time the swells hit Mavericks. Tides and weather were double-checked, and the call was made: the contest’s first heat would start at daybreak, January 20.

Big-wave riders had been watching the wave models, too, with gear packed. Within hours of the announcement, the twenty-four invited contestants boarded flights bound for San Francisco from Africa, South America, Europe, Mexico, and Hawaii. They’ve done this before. In San Francisco, they loaded their long slender boards (guns) into cargo vans, along with bags stuffed with fins, wax, leashes, emergency flotation devices, and wetsuits designed for fifty-degree water. Then, like me, they made the forty-five-minute drive to the sleepy town of Half Moon Bay.

Having grown up surfing at Malibu Pier, I’ve known about Mavericks since it was first publicized in the early 1990s. Before that, big-wave riding was limited to a handful of bold surfers huddled once or twice a year in the lineup at Waimea on Oahu’s north shore—native Hawaiians were likely surfing Waimea for centuries. As big-wave surfers grew in number and boldness, they went looking for other breaks. They found Jaws on Maui, Ghost Trees south of Mavericks, Todos Santos in Mexico, Teahupoo in Tahiti, Dungeons in South Africa.

In the mid-1990s a group of surfers left Los Angeles on a boat bound for Cortes Bank, a submerged island a hundred miles offshore, chasing rumors of eighty- to ninety-foot waves. One of the mission’s members, Surfer Magazine’s Bill Sharp, wrote, “It’s the only time I filled out a will before a surf trip.”

These breaks—and a handful of others that have been discovered since—were either unknown to the surf community or unsurfed thirty years ago. Surfers who seek them out are a different sort, involved in a different sport than those who paddle out at Malibu Pier. As at hundreds of West Coast breaks stretching from Chile to Alaska, the waves at Malibu average three to four feet and peel—“crumble,” some would say—benignly across a rocky point. Not so with breaks like Mavericks. These waves don’t crumble. They rise suddenly from deep water like a threatened cobra, pitch forward, and break from top to bottom over a shallow reef. These waves are heavy. They pack so much force that if a surfer falls, he is often thrown to the bottom and held there for minutes. At best, the experience is likened to being a rag doll tossed in a washing machine’s spin cycle. Downed surfers can lose their sense of direction—which way is up and which way is down—and struggle to the surface with only enough time to grab a mouthful of air before being buried under the next whitewater mass.

Most big-wave riders hire a rescue team that stands by on jet skis. A downed surfer is hard to spot amid the turmoil, but his location is sometimes marked by a “tombstoning” board, which stands upright while pulled down by a leash attached to the surfer below. If possible, a rescuer will rush in and pull him out before another wave hits or before the exhausted soul is dashed against the rocks.

Rescue operators are highly trained and put themselves at great risk to save lives, but they’re not always successful. In December 1994 surfers watched in horror as Mark Foo, one of the world’s most competent big-wave riders, drowned at Mavericks. In 2011 Sion Molosky, a twenty-four-year-old professional surfer, was also lost there.

Greg Long nearly met the same fate last December at Cortes Bank. He and a team chartered a boat to take them out between two large storm fronts. Long was thrown down the face of a sixty-foot wave and slammed against the reef. “I barely made it up for air,” he told me. “When I surfaced, another wave was on top of me. I took three set waves on the head and finally blacked out.” Later, in an interview at his San Clemente home, he would tell me how the experience changed his life.

Greg Long makes a bottom turn on a Todos Santos monster, December 2005.

I had met Long a couple of years earlier when I learned he was a member of the only surf team granted permission by the Chinese government to ride the Qiantang tidal bore. He and a few other surfers timed their trip to coincide with the fall 2009 spring tides. By the time I read about it in Surfer’s Journal, I had already been to China to see the bore and had moved on to studying Newton’s equilibrium theory.

One of the things I’d learned is that inconsistencies in Newton’s theory were surfacing even before it was published. The tide, for example, seemed to behave more like a wave than a bulge. As wave studies progressed through the eighteenth and nineteenth centuries, scientists began to view the tide as a long wave circling the planet—at the speed of a modern jet. After Newton, the next major tide theory, called the dynamic or progressive wave theory, emerged from this view.

I also learned that a tide wave and a Mavericks wave are more alike than not. It’s hard to get our mind around this because we experience them so differently. A Mavericks wave appears on the horizon, rises up, and breaks on shore, all in a matter of seconds. It’s a familiar shape—what most of us expect a wave to look like. A tide wave travels ten times the speed of a Mavericks wave, but it’s so long—ten thousand miles from crest to crest—that it seems to pass slowly. In fact, it passes so slowly—half a day from crest to crest (high tide to high tide)—that we don’t recognize its wave shape.

After reading the story of Greg Long’s encounter with the Silver Dragon (where the tide does have a familiar wave form), I called him. When he told me he was a competitor, I asked if I could meet him at the next contest. “Sure,” he said, “I’ll try to get you on a boat.” And he did. I would be joining him and a few other competitors, including his brother Rusty, on the press boat, along with photographers and reporters from Sports Illustrated and ESPN. We would be positioned alongside the judge’s boat, as close to the waves as we could safely get. For me, this was a dream—to see not only the surf contest close up but also what Mavericks could teach me about waves.

On the morning of the contest, I meet Long at the Pillar Point Marina at 5:00 a.m. He’s tall and sinewy, with brown hair and eyes. Twenty-nine now, he’s been surfing professionally since seventeen, when he won the 2001 National Men’s Open Title. Although he seems composed, I know this is his first big wave contest since the Cortes Bank accident less than a month ago. “I paddled out last night,” he tells me. “The whole Cortes experience rushed in. I was emotional.”

“How are you now?” I ask. “Are you ready?”

“Yeah, I’ll be fine. I do this so often that I’ve learned not to let these feelings carry me away. This sport teaches you to stay in the moment.”

It’s still dark as we descend into the marina. Thick, tangy air settles among the clutter of masts and fishing gear. A foghorn groans offshore, a constant reminder of a waiting ocean. Most boats rest silently, their mooring lines limp in the predawn calm. The few boats preparing for the day are pooled in light while crews, mostly twentysomethings in jeans, sneakers, and hoodies, busily stow gear and supplies: dry bags in neat rows aft of the pilothouse, surfboards athwartships at the stern, sandwiches and water in the galley. Everything must be lashed down, ready for rough seas.

Our boat’s motors are idling as Long and I approach. Rob, the owner, greets us pleasantly but briefly. He slips me two seasickness pills and asks that I sign a waiver releasing him from liability. I do that and down the pills while Long meets with his team to discuss the day’s strategy.

Soon we’re untying lines and easing out of the harbor, along with four or five other boats. The sky pinkens, revealing details of the marina, Half Moon Bay, and the dry California hills beyond. I once read that when looking at waves from afar, you can tell they are big if they appear to be moving in slow motion. That’s exactly the way the waves look at Mavericks as we round the outermost jetty.

Because waves are complicated and elusive, knowledge about them came slowly. In the fourth century BCE, Aristotle noticed that large ocean waves traveled beyond their stormy birthplace, even after the wind had died. Stories of enormous rogue waves arising from nowhere and destroying boats at sea have been part of lore since antiquity. As late as the mid-eighteenth century, some natural philosophers believed that waves were caused by fermentation, which made water swell and explained why waves arrived before a storm.

Leonardo da Vinci, in the fifteenth century, studied waves in their simplest form. Tossing a rock in a still pond, he watched as ripples radiated in all directions. This was simple enough, but eventually the small waves hit the pond’s edge and reflected back in the opposite direction. These passed through the initial waves, sometimes combining with them to form larger waves, sometimes canceling them out, and sometimes forming standing or stationary waves that rose and fell in place. Da Vinci was befuddled—as were scientists for the next five centuries.

Newton hinted that the tide had wavelike qualities. While he was working on the Principia Mathematica, his friend Edmund Halley told him about a strange tide at the Red River in the Gulf of Tonkin (present-day Vietnam). In 1678 Francis Davenport, an Englishman who was surveying the Red River for the East India Company, reported that the Tonkin tides rose and fell only once a day, not twice as they did in Britain. “I must needs confess it different,” he wrote in a letter to the Royal Society, “from all that ever I observ’d in any other Port.” Davenport also noticed that Tonkin’s highest tides didn’t coincide with syzygy (new or full moon). The news shocked English philosophers, who were convinced that all tides behaved like British tides. Halley called it “wonderful and surprising, in that it seems different in all its circumstances from the general rule.”

Newton may not have called it wonderful, since it threatened to undermine his new theory. He added a long paragraph in the Principia speculating that the anomaly was due to two separate tides coming from different directions. If these tides were out of phase, meaning one took twelve hours to reach the Red River and the other took six, they would interfere with each other. The interference might flatten the twice-daily tide and accentuate the once-daily tide. The interference might also stall high tide’s arrival to an extent that it no longer coincided with syzygy. The Tonkin phenomenon was much like what Leonardo da Vinci observed on the pond, where waves of different sizes and phases combine to hatch new forms.

Newton didn’t call the Tonkin tide a wave, nor did he refer to its confusing interaction as wave interference, but he implied that this is what was going on. Years later, his speculations were proven essentially true. Meanwhile, other anomalies were showing up. Sailors, in fact, had been discovering idiosyncratic tides ever since they acquired the skill and nerve to set sail for faraway lands.

The Age of Discovery, which began in the fifteenth century and lasted several hundred years, saw an explosion of worldwide sailing expeditions. Motivated by rumors of undiscovered lands, faster and safer trade routes, and the promise of wealth, hundreds of boats took to the oceans. Most maritime nations—Italy, India, the Netherlands, China, South Africa—were engaged, but explorers from Britain, Spain, and Portugal were the most ambitious. Christopher Columbus crossed the Atlantic and bumped into the Bahamas in 1492. Ferdinand Magellan set off from Spain in 1519; one of his five ships limped back three years later, completing the first global circumnavigation. Sir Francis Drake followed, then Loyola, then others.

Because accurate charts and tide tables were nonexistent, these voyagers had to learn the hard way. Boats were lost—most not at sea, but on reefs as they tried to enter unknown ports. Hard-won knowledge of practical navigation—how to take advantage of wind and weather, the depth of port entrances, the behavior of tides and currents—was coveted. Details were meticulously entered in the ship’s log and guarded as trade secrets, for commercial and military reasons. Most of these explorers had little interest in tide theory; they just wanted a reliable chart for safe navigation. Yet the farther they ventured, the more baffling the tide picture became.

The tides in Europe occur twice daily, with very little inequality. In other words, if high tide arrives at Liverpool at 1:00 p.m. today, another high tide of equal height will arrive roughly twelve hours and twenty-five minutes later. And because Europe’s tides follow the moon, tomorrow’s tides will arrive about fifty minutes later than today’s. This was all empirically understood during the Age of Discovery, and everyone—both sailors and theorists—assumed this general rule applied everywhere.

Exceptions kept piling up, however. In the Persian Gulf, Philippines, and parts of China and Australia, sailors found once-daily, not twice-daily, tides. In the Gulf of Mexico they found tides that seesawed weekly between once- and twice-daily. In Tahiti the tides seemed to follow the sun, not the moon, arriving like clockwork at noon and midnight instead of slipping fifty minutes later each day. Most of the Pacific had tides with strong and variable inequality, which meant that during a few days each month, there was a large difference in height between the two daily high tides as well as the two daily low tides (see figure on pages 136 and 137).

The general rule was unraveling at home, too. The Solent inside the Isle of Wight on the English Channel had a double high tide, and so did Le Havre on the channel’s French side. Britain’s port of Portland and a few Dutch ports had double low tides. And whereas most places had one or two tides a day, Courtown on the Irish Sea had four.

All this pointed to something amiss in Newton’s equilibrium theory, which essentially assumed that tides behaved the same everywhere. Newton can be forgiven, since his focus was primarily on what happens in the heavens, not on earth. He wanted to show how the movements of celestial bodies, coupled with that mysterious force called gravity, could stir the oceans. For his purposes, he stripped the earth of its complexities, arrested its orbital motion, jettisoned its continents, and covered the whole thing with deep water. On that blue planet, he was able to demonstrate how the heavenly forces could raise two humps, one pulled by gravity toward the moon and sun and one “fleeing” by centrifugal force on the earth’s opposite side. These humps—what we experience as high tide—were free to follow the moon and sun wherever they roamed. It was genius. But it was only half the story.

When the real earth, peppered as it is with landmasses, islands, and continental shelves, is reintroduced to Newton’s simplified model, the scene completely changes. Suddenly the watery humps that peaceably followed the moon and sun are blocked. As on da Vinci’s pond, they bump into land, reflect back, squeeze through narrow passages, and drag on shallow bottoms. Some of them are in phase and some out of phase. Some are standing and others are progressive. To further complicate matters, they do all this on an orb spinning up to a thousand miles per hour.

If the study of tides were divided in two parts—astronomy (what happens up there) and fluid dynamics (what happens down here)—it could be said that Newton got the first part right. In fact, he got the first part so right that the equilibrium theory continues to be used as an idealized tide model. The second part, what happens down here, is unimaginably messy. Scientists are still working it out.

By the early eighteenth century, it was dawning on theorists that there were holes in Newton’s theory. With the hope of uncovering a discernible (and predictable) pattern, they called for long-term observations. In 1701 the Académie Royale des Sciences of Paris sponsored observations at Dunkerque, Le Havre, and Brest on the north coast, and within fifteen years they had data (times and heights for high and low tide) for all major French ports. In 1738 the Paris Académie, still unsatisfied with the progress of tide theory, announced a contest for the best essay on “the flood and ebb of the sea.” The prize was shared two years later by scientists from four countries. One, a Frenchman, rejected Newton’s theory in favor of Descartes’s concept of a soupy ether pressing against the oceans. The other three winners were Swiss, Scottish, and Dutch, all building on Newton’s equilibrium theory. Even with these developments, tide prediction tables, which were produced privately using secret methods, were still largely inaccurate.

By midcentury, observations were initiated in England at London, Liverpool, Bristol, and Plymouth. In those years, water levels were read on a vertical staff, much like a yardstick, lashed to a dock piling. Astronomers, shipwrights, and dock masters volunteered for the job, which was done more or less hourly, day and night (the first auto-recording gauge wasn’t invented until 1830).

A sampling of different tides. Note Galveston’s standing high tide at quarter moon; Tahiti’s consistent noon and midnight high tide; New York’s successive highs and lows of near equal height (semidiurnal equality); Los Angeles’s mixed tides—successive highs and lows, sometimes equal and sometimes not; and Southampton’s double high tide.

Among other things, these initial observations revealed that tides progressed wavelike, just as the English monk, the Venerable Bede, had suspected a thousand years earlier. “Those who live to the north of me,” Bede had observed from his monastery overlooking the Northumbrian coast, “will see every sea tide both begin and end much earlier than I do, while indeed those to the south will see it much later.”

The French observations confirmed that if high tide arrived at Brest at 2:00 p.m., it would arrive at Le Havre six hours later and at Dunkerque three hours after that. Low tide would follow the same pattern: arriving first at Le Havre, and finally at Dunkerque.

By the latter half of the eighteenth century, waves had become the central focus of tide studies. Little was known about them, but enough to glimpse how their behavior might unlock the tide’s mysterious workings in the real ocean. This new direction, called the dynamic or progressive wave theory, was a major stepping-stone between Newton’s theory and the current harmonic theory. In it, Newton’s watery bulges were visualized as large, long waves racing at 450 miles per hour around the Southern Ocean, where bothersome continents or shallow water wouldn’t interrupt them. From there, they spread northward into the Atlantic, Indian, and Pacific Oceans.

Our boat pitches and rolls in the swell as we approach Mavericks. I’m drowsy from the Dramamine, but it beats being sick. The sun is up, and the first six surfers paddle out. Rescue teams zip here and there on jet skis. The San Mateo County sheriff’s boat stands by, as does a medical emergency boat. A couple of kayakers and a few local surfers have paddled out from the marina. As the day wears on, thirty or forty boats bob in a cluster, well away from the impact zone but as close to the waves as the officials will allow. Occasionally a gray whale surfaces offshore, its misty exhale hanging in the light breeze.

The waves come in sets of three or four, warping from the horizon like blown glass. Even at this close range, they seem to build in slow motion. For most of their journey, they’ve been able to speed along in deep water without feeling the bottom. Now, encountering the reef, they’re transformed. They drag in the shallows and steepen to a point of instability. As the bottom of the wave slows, the upper lip rushes forward, silent and trembling, until the whole thick slab collapses. The wave’s leading edge hits the water below with a deafening crack, as if the ocean were concrete. Masses of water bounce into the air. Seconds later, a whitewater avalanche emerges from the chaos and rumbles toward shore. During sets, the impact zone—where the waves break—is draped in a haunting mist.

I watch several competitors paddle for these watery mountains. Their performance is judged by the biggest wave, the most critical drop, making it (not falling), and sportsmanship-like conduct (not putting themselves or others in undue danger). Each heat is forty-five minutes, with the top six competing in the final heat. These six often agree to split the prize, in this case $50,000, a tradition inspired by Long when he won the contest in 2008.

During a later heat, I watch through binoculars as Long goes for a large set wave. He puts his head down and paddles furiously. The wave comes up from underneath, and only at the very last moment, high on the lip, does he catch it. He stands up and hangs for a second or two. Then, as if the wave has decided to allow him in, he races down the face and makes a long, arcing bottom turn.

“It’s all in the drop,” he tells me later. “These waves are moving about thirty-five miles per hour. It’s hard to paddle fast enough to catch them. When you get in, you’re usually high on the lip. It’s a critical moment. You hang there weightlessly, looking down a cliff and trying to set your position for the drop. The wave is made or lost in those first moments, which feel like eternity. If you make the drop and the bottom turn, the rest is icing. If you don’t make the drop—if you get hung up on the lip or don’t get positioned on the board right—that’s the end. You’re thrown down the face, and a wall of water three stories high unloads on you.”

At twenty-plus feet, the waves today are plenty big, but Mavericks has seen larger. In November 2001 they topped sixty-five to seventy feet. Brazilian Carlos Burle surfed a record-breaking sixty-eight-foot wave that day. His record has been broken several times since—at Cortes Bank, Jaws, and most recently Nazare, Portugal, where in 2013 and 2014 waves up to a hundred feet may have been ridden. It’s difficult to confirm the height of these waves, since there is no consistent and verifiable method of measurement.

When big-wave surfing was discovered in the 1990s, it was thought that these monsters were moving too fast to paddle into. Surfers were towed by jet skis and whipped into the wave well before it began to break. By doing this, they avoided the treachery of hanging up on the lip as well as making the drop.

In 2008 Long and a small group of friends wanted to find out if they could paddle into these giants. They studied wave dynamics and tested new equipment: longer, narrower, heavier boards, designed for paddling faster. “Eventually, we found out it can be done,” he says, “but it requires a different set of skills than tow-in. You have to know more about the wave, how it’s moving, where the peak is forming, how much current is coming up the face, where it’s going to break. The takeoff zone is narrow—if you’re too far one way or the other, it could mean missing the wave or getting hurled. And your only source of power is your hands.”

Long doesn’t know the size limit for waves that surfers can paddle into, but he wants to find out. Records are broken frequently. Shawn Dollar paddled into a fifty-five-footer at Mavericks in 2010, and Shane Dorian caught a fifty-seven-footer at Jaws a year later. Shawn Dollar holds the current record with a sixty-one-footer at Cortes Bank in 2012. “There’s always the hope that there’s a bigger wave out there,” says Long. “You never know when it’s going to happen, or where. The biggest waves we’ve ever seen could show up ten days from now—or ten years from now. That day will happen, and you can bet there’ll be surfers ready for it.”

These big waves are almost always born in offshore storms, traveling in organized sets across vast distances. As wind-generated waves, they’re common and conspicuous. Benjamin Franklin, who was fascinated by the ocean, wrote in 1774: “Air in motion, which is wind, in passing over the smooth surface of water, may rub, as it were, upon that surface, and raise it into wrinkles, which if the wind continues, are the elements of future waves.”

These first wrinkles are what we now call cat’s paws or capillary waves. They have a period (the time between the passage of two crests) of fractions of a second. If the wind blows hard enough, long enough, and over a large enough distance (fetch), these wrinkles build into waves, at first a foot or two high and eventually into a fully developed sea of twenty-foot-plus waves.

These waves leave their stormy nursery and traverse the oceans in organized sets, or swell trains, with periods of fifteen to twenty seconds. Surfers and sailors much prefer these over local wind waves, which tend to be short, steep, and “confused.”

All wind waves—even a hundred-foot rogue—begin as a wrinkle. With life spans up to several days, they usually expel their last breath when they break on a reef or beach. Once they break, their life is over.

Tsunamis, storm surges, and tides are waves, too, but with different characteristics. Tsunamis (Japanese for “harbor waves”) are spawned by seismic events, volcanic eruptions, landslides, or earthquakes; a meteorite, if it hit the ocean, could also cause a tsunami. They’re not as common as wind waves, but they’re more common than we realize. Catastrophic tsunamis occur about twice a decade—mostly in the Pacific Ocean—but smaller ones happen several times a year. In the open ocean, a tsunami, like the tide, is a long, low wave that travels about 450 miles per hour. With a period of thirty to ninety minutes, these waves are so long and low—just a foot or two high at sea—that they’re virtually undetectable by boats offshore. Yet when tsunamis approach a coast and begin to feel the bottom, they slow down and steepen just like a Mavericks wave, sometimes towering to a hundred feet and causing horrible damage and loss of life.

A storm surge is created by a combination of low barometric pressure and high winds associated with a storm front. Essentially it’s a single hump of water—as high as forty feet—traveling directly below a storm. When the storm makes landfall, so does the surge. Like tsunamis, storm surges occur far less frequently than wind waves, but they’re often memorable. Combined with a large tide, as in the case of Hurricanes Katrina and Sandy, they can be catastrophic. Katrina’s storm surge, which hit the Gulf Coast in 2005, was twenty-two feet, the largest in U.S. history (Katrina’s total tide-plus-storm surge was a record thirty-four feet). Sandy’s, which made landfall in New York and New Jersey in 2012, was nine feet.

Some waves feel the bottom and some don’t. If they do, they’re shallow-water waves; if they don’t, they’re deep-water waves. Whether they’re one or the other is determined by the wave’s length (distance between crests) relative to water depth. If a wave is traveling in water with a depth of less than half its wavelength, it’s a shallow-water wave. In other words, a wave with a length of ten feet is a shallow-water wave if it’s traveling in a depth of five feet or less.

With a wavelength of eighty to a hundred miles, a tsunami is a shallow-water wave, even as it crosses the deepest ocean basins. The oceans would have to be forty to fifty miles deep to allow it to move without feeling the bottom.

Tides are shallow-water waves, too. With a period of just over twelve hours and a wavelength of ten thousand miles, they would need an ocean five thousand miles deep to race at full speed around the earth. The ocean’s average depth, however, is only three miles. So, like a tsunami, the tide constantly drags its feet on the sea’s bottom, adding layers of complexity to its shape and timing.

There’s another important difference between these waves. Wind waves, tsunamis, and storm surges have a beginning and an end. They’re born of a single event—a puff of wind, a storm, or an earthquake. As free waves, they travel away from the event without receiving further energy from it. Although they can traverse enormous distances, they eventually perish for loss of energy. A free wave behaves like a child on a swing whose parent gives him just one push and walks away. With no further pushes, the child sweeps back and forth in smaller and smaller arcs until the initial energy dies out and the swing stops.

Although the tide can act like a free wave at times, it’s primarily forced, not free. That means its “parents”—the moon and sun—push continuously. They never walk away—not today, not yesterday, not tomorrow. Consequently, a tide wave, unlike a wind wave or storm surge, has no beginning or end. It never was a wrinkle. It doesn’t break and die.

From my perch on the bow of Rob’s boat, I watch another set roll in. The outermost wave rears up a third again as high as the others, perhaps the largest and steepest we’ve seen today. Peter Mel catches it and screams down the face, his arms stretched winglike for balance. The wave’s lip feathers; a white plume blows off the back side. Through binoculars, I can see the wave sucking water off the reef and up its steepening face. The lip reaches skyward and arcs forward, creating a classic almond-shaped hollow. It’s a gorgeous wave, monstrous and silky, breaking cleanly across the reef. Mel makes the drop and bottom turn, then stalls on the shoulder, positioning himself for the barrel.

In a moment he’s gone, folded into the wave. Has he fallen? There’s no way of knowing. The wave’s open end is choked with spray. If he’s in there, he’s crouched low, head ducked. His right hand is trailing, touching the wave, feeling its pulse. Being in the barrel is the most intimate experience of a wave. Every surfer dreams of it. Here, mind, body, and ocean are caught in the most exquisite and ferocious balance. Time stops. The kinetic energy is wound so tightly that one wrong move, as slight as catching a finger on the water, snuffs out the experience.

Our eyes are riveted on the wave’s leading edge, which huffs and snorts like a heaving animal. Just when it seems impossible that Mel could still be standing, he’s spit from the barrel.

We’re stunned, relieved. Everyone, including the other competitors, lets out a cathartic cheer. I overhear a judge say, “That might be the wave of the day.” No one would disagree. It’s a wave few of us will forget, especially Mel.

Some waves are like that: unforgettable. Of the thousands—millions—that come and go, a few stand out. Surfers like Mel and Long remember waves that gave them the best—and the worst—rides. Long, I’m sure, won’t soon forget the wave that almost killed him at Cortes Bank.

Sailors, too, remember certain waves. I won’t soon forget the tide wave that almost sank Crusader at Kalinin Bay in southeast Alaska many years ago. Nor will I forget a wave I encountered while making a 1,500-mile passage from Florida to the Virgin Islands in the early 1980s. A friend and I had been sailing in a storm for several days. We had taken all the sails down, but my twenty-six-foot sloop was still “sailing” at hull-speed under bare poles, blown by forty-knot winds. The waves were more than twenty-five feet, each one coming from behind, lifting my small sloop’s stern and passing under. But one wave reared up perhaps one and a half times as high as the rest. I could see its blackened face looming above the others, smothering the horizon.

I had only one thought: if this monster breaks, it will be the end of us.

I yelled to my friend in the cabin to brace himself as our little boat began to climb—up and up and up. Then, suddenly, we rushed forward and surfed down the face. At the bottom, we broached to starboard and were overwhelmed by whitewater that snapped lashings and carried away whisker poles, extra gas cans, life jackets, and the self-steering vane. I would have been carried away too if I hadn’t been attached with a life harness. After the wave passed, my friend and I bailed several hundred gallons from the cabin. We were shaken and bruised—but grateful to be alive.

Waves don’t have to be big or menacing to catch our attention. Most anyone who has spent time on or near the ocean remembers a wave or two, perhaps one we admired for its shape or grace as we strolled the beach or one that caught us by surprise and tumbled us amid the shore break as a child.

Traditional Polynesians made an art out of remembering waves. While most of us see the ocean’s surface as a blur of motion, they saw it as a pattern to navigate by. When miles at sea, they could tell by the crisscrossing swell behavior exactly where they were and the course they needed to steer—and for how long—to get home. This knowledge didn’t come quickly, but was acquired over thousands of years of practice.

They even named their waves: rilib was the dominant northeast swell, bungdockerick was a southwest swell, and buoj was the intersection of east and west swells. How these swells bend and twist around islands was mapped on stick charts and memorized. At sea, a good navigator could lie in the boat’s hull and know his whereabouts just by sensing the rolling motion of the swell. Navigators in these cultures, identified with a “gift” at childhood, served as apprentices for years before taking charge of a seagoing boat.

Greg Long studies waves as diligently as a gifted Polynesian navigator. “Each break,” he tells me, “has a personality that’s determined by the bathymetry—water depth, shape of bottom, size of reef, and so on. Bathymetry never changes. It can focus waves or diffuse them. Yet any given wave on any given day, even hour to hour, is unique depending on the swell size and direction, wind, and tide. It’s always shifting. Onshore winds flatten waves, and offshore winds stand them up. A difference of a few degrees in swell direction can influence how a wave will break too. At Mavericks, the wave is predictable and pretty clean. It usually breaks in the same spot every time. At Jaws and Dungeons and Cortes, the wave can stand up and break at different places on the reef, so you’re always on edge, especially if you’re trying to paddle in.”

Tides also play a role in shaping surf breaks. The flood can push a swell in; ebb can flatten it. Some breaks only “show” for an hour or two during the right tide or when just enough water is over the reef. Some breaks are too dangerous to surf at low tide. “I had one of my biggest accidents at a low tide at Mavericks,” says Long, “and learned not to do that again. If there’s too little water over the reef, the wave stands straight up and breaks like one large slab. I fell on one of those and was swept across the reef into deep water. I probably went down fifty feet. It was like going over an underwater waterfall. I went down so fast that I broke an eardrum. That turned into a two-wave hold-down. I’ve experienced about six two-wave hold-downs in my life, and four were at Mavericks.”

When not surfing, Long works out five hours a day. His routine includes yoga, swimming, mountain biking, and breath-holding exercises. “My father was a lifeguard and taught my brother and me respect for the ocean,” Long says. “I take that very seriously. People think I’m crazy, but I’m always rehearsing worst-case scenarios in my mind, trying to figure out how to prepare for them.” Long eats mostly raw food, designs surfboards, and tests safety equipment. “I have a team I like to surf with—guys I trust. We rehearse different rescue scenarios. I won’t go out at a break like Cortes without a six-man safety team.”

Long also studies wave models. On his computer, he keeps seven years’ worth of wave, storm, and tide statistics. “I watch almost all the big oceans—the Atlantic, Indian, North and South Pacific—daily,” he says. “When I see a storm crop up, I can superimpose my statistics and predict where and when the waves will hit and how large they’ll be.”

Among elite surfers, Long stands out for his interest in and knowledge of waves. Surf writer Brad Melekian remembers an afternoon phone call from Long a few years ago when the two were supposed to meet at a yet-to-be-determined break the next day. “First thing I hear,” Melekian says, “Greg’s on Highway 1, driving to Mavericks. He pulls over, takes out his laptop, checks the buoys. Calls and tells me he’s just booked a boat for Cortes. Then calls back fifteen minutes later: ‘We’re going to Shark Park’ [near Santa Barbara]. Fifteen minutes later: ‘Mavs.’ An hour later: ‘Okay, Todos.’ And then finally it’s back to Mavs. That’s what he does. He’s processing and analyzing nonstop.”

A handful of eighteenth-century natural philosophers were processing and analyzing waves too, most notably William Whewell, George Airy, and Pierre-Simon Laplace. In the context of the progressive wave theory, understanding wave behavior was the next best thing to understanding the tides.

Whewell (1794–1866), an Anglican priest and master of Trinity College, Cambridge, pushed for more field observations. When his attention turned to the sea, he was thirty-six, already an accomplished scholar of mineralogy, architecture, history, astronomy, and poetry. He’s perhaps best known for his writings on the philosophy of science, but his interests were eclectic. He wrote sermons, lectured on Gothic architecture, translated Johann Goethe, tutored Alfred, Lord Tennyson, and coined the terms ion, anode, cathode, and physicist. In 1833, after the poet Samuel Taylor Coleridge complained that “natural philosopher” was the wrong term for a person digging in fossil pits or performing technical experiments, Whewell offered the word scientist. If “philosopher” was “too wide and lofty a term,” Whewell said, “by analogy with artist, we may form scientist.” And so it was.

Prior to Whewell’s involvement with tide studies, John Lubbock, a fellow Trinity mathematician and astronomer, dug into the Liverpool and London tide records, the oldest sustained observations in Britain, in search of a long-term pattern that could be used in developing a reliable tide prediction method. Prediction at that time was a matter of practical knowledge and relied on the fact that every port had a unique and unchanging relationship between the moon’s passage overhead and the arrival of high tide. The method was called Establishment of Port. In practice, a sailor journeying down Britain’s coast knew that the Liverpool harbor entrance, for example, was shallow and only passable at high tide. He also knew that the establishment at Liverpool for that night was plus one hour and twenty minutes. With that knowledge, he would stand off the harbor entrance until the moon reached its zenith, wait one hour and twenty minutes, and sail safely in.

The term Establishment of Port was coined by Whewell, but the principle was surely recognized and used by early navigators. In the eighth century, Bede wrote: “In a given region the moon always maintains whatever bond of union with the sea it once formed.”

Lubbock was less interested in Establishment of Port and more keen on the secretive calculations behind the tide tables produced by private parties in Liverpool and London. The Liverpool tables had been continuously produced by one family for fifty years (since 1770). Lubbock eventually won their trust and was able to review their methods, which were loosely based on the work of Daniel Bernoulli, a prizewinner of the 1740 Paris Académie contest.

Lubbock presented his findings at a Royal Society meeting in 1830. Whewell was there and, inspired, soon took over where Lubbock left off. True to his wordsmithing instinct, he called the pursuit tidology (the name never stuck), and in the following twenty years he published fifteen tide papers in the Philosophical Transactions.

Whewell was more ambitious than Lubbock. He recognized that while his colleague’s effort was admirable, it would ultimately reveal only the tide pattern for a single port, such as London or Liverpool. Because the tide varied considerably from port to port, Lubbock’s method wouldn’t reveal a global pattern. If there were a larger pattern, figured Whewell, it would be revealed only through simultaneous observations at many ports. By doing this, a line could be drawn connecting the places of high tide at any given hour. Whewell called such lines co-tidal.

Whewell couldn’t organize a large set of observations on his own, so he appealed to Sir Francis Beaufort, head of the Admiralty’s Hydrographic Office. Beaufort, who would develop the Beaufort Scale of wind speed still in use today, responded enthusiastically. While Whewell wrote instructions for observers, Beaufort ensured the cooperation of more than four hundred Coast Guard stations around the British Isles. For two weeks in July 1834, tide observations were made every fifteen minutes. When the data came back, they revealed an odd picture in the North Sea (then called the German Sea). Whewell proposed a second experiment to confirm the results, but Beaufort was already thinking bigger. He wanted to expand the experiment internationally.

In June 1835 the two men coordinated history’s first large-scale international scientific experiment. More than six hundred stations participated in a three-week survey: five hundred in the British Isles, twenty-eight in the United States, twenty-four each in Denmark and Norway, eighteen in the Netherlands, sixteen in France, and a dozen each in Belgium, Spain, and Portugal.

The experiment produced sixteen thousand sets of data. The daunting analysis was undertaken by three clerks from the Admiralty (computers, as they were called). It took months. Anxious for the results, Whewell wrote to a friend, “I shall have such a register of the vagaries of the tide-wave for a fortnight as has never before been collected, and, I have no doubt, I shall get some curious results out of it.”

He had no idea how curious the results would be. The experiment, he expected, would confirm the tide’s northward progression from the southern reaches of the Atlantic, with high water arriving at roughly the same time on opposite coasts. When the tide got to the British Isles, it would pass the English Channel (due to its narrowness) and speed northward around the northern end of Scotland before flooding south into the North Sea.

The picture that emerged from the mass of data, however, showed that the tide’s progression in the North Sea was circular, not linear. It looked and functioned like a pinwheel, with a hub at its center and spokes radiating outward. These spokes circled counterclockwise (see figure on next page). The center hub implied a “point of no tide.” The farther out on the spoke, the larger the tide. Additionally, it appeared that the North Sea, as small as it is, had more than one rotary system, as Whewell called it, and perhaps as many as three.

North Sea amphidromic systems, as discovered by William Whewell in 1835.

The Astronomer Royal, George Airy (1801–1892), ridiculed the notion of rotary systems. He was keen on wave study, too, and had learned by testing in a laboratory channel how waves bend, reflect, stand, interfere, and refract. He figured the North Sea anomaly was explained by wave interference, just as Newton had explained the Tonkin tides earlier.

Whewell’s discovery was anachronistic, as if he had accidentally opened a box that was not due to be disturbed for another fifty years. What was he to make of these spidery things? If they were in the North Sea, were they in other oceans too? At Whewell’s urging, the Admiralty sent out a ship in 1840 to confirm that there was, in fact, little or no change of water level at the “point of no tide.”

Whewell wanted more information. Twice he petitioned the Royal Navy to launch a worldwide two-year ocean expedition to “hunt” the tides. When the navy showed no interest, Whewell shifted his focus back to the data he had at hand but met a dead end there too. In 1866, when the results of the International Tide Experiment were being debated and analyzed in Europe, reports were coming from the South Atlantic that the tide wasn’t behaving as it should down there, either. Instead of progressing systematically northward, high tide seemed to seesaw in an east-west fashion, from one coast to the other.

Captain Fitzroy, master of the HMS Beagle that took Charles Darwin around the world from 1831 to 1836, delivered the most damning news for those still clinging to the progressive wave theory. From years of firsthand experience, he reported that there wasn’t a noticeable tide progression along 1,800 miles of Africa’s coast, from the Cape of Good Hope to the Congo River, and that the South American coast around the Plata River had almost no tide. Fitzroy proposed that each ocean might have its own tide that sloshed back and forth, just as Galileo had observed in the jugs of water while on a boat in Venice.

George Airy agreed but called the Atlantic tide a standing or stationary wave. From his experiments, he knew that a standing wave in a channel rose and fell alternately at each end, with a node of no motion in the center (like a bathtub full of water when we rock back and forth). If this were the case in the Atlantic, then the tide would rise and fall on the east and west coasts but not in the midocean, which would explain why offshore islands generally have small tides.

Whewell’s speculation, not surprisingly, was that the Atlantic tides behaved like a North Sea pinwheel, but he was unable to prove it. In an 1847 lecture to the Royal Society, he admitted, “I do not think it likely that the course of the tide can be rightly represented as a wave traveling S-N. . . . We may much better represent it as a stationary undulation, of which the middle space is between Brazil and Guinea [where] the tides are very small.”

French mathematician Pierre-Simon Laplace (1749–1827) died before seeing the results of the International Tide Experiment, but he had already seen beyond it. Often called the Newton of France, Laplace was distinguished for his genius in mathematical formulations, many of which are still in use today. Like Newton, his attention to tides was fleeting compared to the main body of his work, but it had far-reaching implications. He called the tides “the thorniest problem in astronomy.”

In Laplace’s five-volume masterpiece, Mécanique Céleste, he introduced equations to address the complicated interactions of tide waves on the real earth. He recognized that there was more to the ocean tides than a simple wave progressing around the planet. Instead, he described how each ocean might have its own response to the tide-generating forces and that that response might be defined by many factors, including the size and shape of the basin, the depth of the water, the ruggedness of the bottom, temperature, and so forth. Using calculus and trigonometry, he developed several highly sophisticated equations to account for this, equations that turned out to be nearly impossible to solve without modern-day computers, which wouldn’t be in use for another 150 years. He never fully solved them himself. They looked like this:

In my quest to understand the tides, I’ve sat with many oceanographers who were eager to share their knowledge. Even when I begged them not to, they often turned to equations, insisting on their clarity and elegance. I agree, and admire equations like those above as an expression of the tide, just as a sail’s shape is an expression of the wind or a surfboard’s shape is an expression of a wave, but I don’t have a clue what these equations mean.

Hidden within the unsolved Laplacian equations were the seeds of modern harmonic tide theory, which views the oceans as vibrating basins that respond to the influences of the moon and sun. Also hidden in the equations was the solution to global tide prediction, which was not to be deciphered until the late nineteenth century.

Like Laplace’s equations, Whewell’s concept of rotary tides laid asleep for many years, not to be awakened until the early twentieth century. By then, the Coriolis effect was understood: the earth’s rapid rotation makes wind, waves, storms, and even baseballs veer to the right in the northern hemisphere and to the left in the southern hemisphere. Rollin Harris (1863–1918) of the U.S. Coast and Geodetic Survey saw in 1904 that the tides veered, too. In fact, the tides veered so dramatically that they circled around a center point in exactly the same way Whewell had seen in the North Sea. And they were everywhere (see figure on next page).

These circular systems reminded Harris of an ancient Greek naming ceremony called amphidromia (“run around”). About seven days after a child was born, family and friends gathered to drink wine, eat octopus and cheese, hold hands, and dance in a circle around the newborn. In some cases, the child was ritualistically carried around the household hearth. Harris, evidently more of a romantic than Whewell, called these pinwheel-like tides amphidromic systems or amphidromes. Like the Greek ritual, an amphidrome has a center hub where, as Whewell proved, there is little or no tide. The arms or spokes rotate, with the highest tides in each amphidrome occurring farthest from the center hub.

Some—not all—of the world’s amphidromic systems.

The Pacific has four large amphidromes. One sits west of Baja, with its long arms sweeping up and down the North and South American coasts. The progressive wave theory, like Newton’s theory, was not completely wrong. What wasn’t thrown out—and is still part of the tide story today—is that these circling arms are indeed waves traveling at 450 miles per hour.

The last heat finishes at Mavericks as the late-afternoon sun turns the California hills orange. We sail back to Half Moon Bay for the award ceremony. No one is surprised when Peter Mel wins. Long comes in third, but all six in the final heat split the $50,000 purse. “We agreed to do that at the start of the heat,” says Mel, a native of Santa Cruz, “because it takes the pressure off. It usually brings waves, too, and that’s what happened today.”

In August 2013 I meet up with Long again, at his San Clemente home. The Cortes Bank accident of nine months ago is less raw, but still on his mind. “I knew the waves were going to be big that day,” he says, “the offshore buoys were reporting a fourteen- to fifteen-foot swell at nineteen seconds. That would mean up to eighty-foot faces at Cortes.” Long assembled a team of trusted surfers and rescue operators. On the evening of December 22 they met at Newport Harbor and loaded their gear and six jet skis aboard a 120-foot charter boat. They left the harbor at 10:00 p.m. and arrived at Cortes early the next morning.

All day, sets rolled in with two waves each. As a rule, Long never paddles for the first or second wave of a multiwave set, for two reasons. First, if he falls, he risks being trapped in the impact zone where the rest of the waves break. Second, Long (like most other big-wave riders) is always hunting for the biggest wave, which is almost never the first wave in the set.

On that day at Cortes, Long took off on an early wave of what turned out to be the day’s only five-wave set. He made the drop, but the wave closed out as he finished his bottom turn. Then he fell.

He was thrown onto the reef and buried in thirty feet of whitewater. “When the wave let me go, I swam for the surface,” he says, “but just as I was about to get a breath, the next wave broke on top of me and knocked the wind out of me entirely. I was pushed right back to where I had been fifteen seconds ago, with no air in my lungs.” Being held down for twenty to thirty seconds, Long explains, is something all big-wave surfers are accustomed to. They train for it. To be buried for twenty-five to forty-five seconds in a two-wave hold-down, however, is highly unusual and, in his words, “terrifying.”

But Cortes Bank was different. It was a “perfect storm,” says Long. The second wave pushed him down to about fifty feet. “I was completely out of air,” he says. “My muscles were spasming. I’ve never felt that much pain. I also knew my bloodstream was still saturated with oxygen and that the body can usually survive longer than we realize.

“At that point,” Long continues, “it became a mental battle. To survive, I knew I had to separate from it mentally. My yoga practice has helped me with that. From a physical side, the exercises have expanded my lung capacity, and on a spiritual side, it’s taught me the value of meditation.”

Long was still deep underwater when he heard and felt the third wave pass. He’d been down for about a minute and knew he was going to black out. He had a choice: he could black out down there, or he could fight for the surface, where the rescue team would have a better chance of finding him. He grabbed his leash, which luckily was still attached to the board, and climbed. At the same time, he felt himself separating from his body, letting it go.

Just as Long reached the tail of his tombstoning board, he blacked out. A fourth wave washed over before he surfaced, facedown. The rescue team, including two emergency medical technicians, pulled him out and raced him back to the support boat. The Coast Guard was called. For about a minute and forty-five seconds, Long had no pulse. “That part of the experience is less clear,” says Long, “but I know I left my body at least a few seconds before I blacked out.” Clinically, he had drowned.

Long was coughing blood when he regained consciousness. In such cases—nonfatal drownings—the victim often suffers brain damage from oxygen deprivation. As night fell, a Coast Guard helicopter arrived and flew him to the University of California–San Diego Medical Center. Long was lucky: he was released from the hospital the next day, Christmas Eve, with no further complications—at least physically.

“When I met you at the Mavericks contest in January,” Long says, “I was still shaken up. The accident had happened a few weeks earlier. I didn’t know what I was doing or even why I was surfing anymore. I was just going through the motions, trying to power through it, by sheer ego, pretending I was okay. But I wasn’t. I was terrified. Nothing felt the same.”

It seems that most people would want to put a harrowing experience like this behind them—to erase it from memory. Long does the opposite. He keeps circling back to the Cortes incident, reliving every detail through dreams and meditation, in search of more knowledge, more insight, more lessons—a search that is like his thirst to understand waves and the ocean.

“Since then,” Long reflects, “I haven’t stopped surfing. I’ve been following nearly every big swell as I have my entire career. Each session I go out, I regain some confidence and comfort. Even with the fear, I have no regrets about the accident. Everything’s a lesson—and Cortes was a huge one for me. Now I’m getting through it and living life with a different perspective on big-wave riding—a different set of challenges or rules than the next guy, who’s maybe never had a bad wipeout. I don’t care anymore who surfs the biggest wave or wins the contests. I only care about passion—about loving what you do. And what I love to do is find and catch big waves.”

These color photographs dramatically illustrate tidal range across the United Kingdom. Each pair is taken from the exact same position—at low tide (top) and high tide (bottom).