20,000 to 36,200 feet (6,000–11,000 m)
The hadal zone in the sea comprises the trenches all around the Pacific, especially in the western Pacific, as well as the eastern, central and South Pacific off the coast of Central and South America. There are also trenches in the northeast Indian Ocean off Indonesia, the northeast Caribbean and the South Atlantic near Antarctica. If most of the seabed of the deep ocean consists of the abyssal hills and plains, the hadal zone is the area where the plains drop off in jagged rocky crevasses that plunge up to three miles (5 km) deeper than the abyss, to the bottom of the world, to the muddy pits closest to the Earth’s core. These wide trenches mark where the ocean’s spreading seafloor plates have collided with land-bearing plates. The movement of the tectonic plates in these potent earthquake zones produced the trenches, just as it created the long mountain rift valley of the great midocean ridge.
As the iMonstercam descends into the seemingly bottomless trench, the fish become ever smaller. Some remain black, but others have become dirty white or even colorless, lacking all pigment. In this zombielike land, there seem to be fewer animals, but the expectation of what further strange forms might be seen lurking has grown considerably. And our curiosity about what might crawl on or in the ooze at the bottom of the sea is what keeps our interest ticking. Will the bottom prove to have more life than these deep-water layers?
It is even quieter down here in the trenches. Looming out of the black, might we see the secret submarines of the world’s powerful navies (they are said to use the trenches in the Pacific)? Navy submarines strive to be quiet and to listen; they would hear us before we ever hear them. A few submarines could be crawling around us, and we would never know.
The persistence of the blackness at this level (how much blacker can it get?) is no different from that of the abyssopelagic or bathypelagic waters. But the ever greater distance from the photic zones, from the source of the sun, and the dramatically increasing pressure make this as forbidding a place for humans—and animals in general—as anywhere on Earth.
Until now, the pressure has intensified through every descending zone, but the difference between the top and the bottom of each zone is much less than it is in the hadal zone, which occupies up to half the depth of the sea. As we enter the hadal zone, the pressure is 600 atmospheres (600 times what we experience at the surface), which translates to 8,820 pounds per square inch (psi). But that’s just the starting point. When we reach bottom—up to 36,200 feet (11,033 m) deep in the Pacific trenches—the pressure will exceed 1,100 atmospheres, or 16,170 psi. That’s more than eight tons pressing on every square inch of the iMonstercam.
Some would say the hadal zone is aptly named, maybe even an understatement, for this black, frigid, high-pressure hellhole. But this perception is true only for those who cannot stand the pressure, the cold, the darkness, the comparative lack of food. According to some evolutionary biologists, the deep sea represents the margins, where species that couldn’t survive in the upper layers were forced to go. Yet to those animals adapted to living here, it’s home.
For all the extremes, the hadal zone offers constancy. Any species that can more or less count on the same environmental conditions—day and night, season to season, year by year—has tremendous advantages. Deep-sea species are never bothered by hurricanes, ice ages or the effects of El Niño. Things move ever so slowly in the deep sea, but the trenches miss most of that too. The natural hazards of deep-sea life, such as occasional underwater earthquakes and volcanic eruptions, however, can be cataclysmic when they happen.
Historically, the quest to find out whether anything lived at the bottom of the sea followed two main threads. The first part was simply to drop dredges and try to haul up bottom fauna from ever deeper portions of the bathypelagic, abyssopelagic and hadal zones. The second was a far more challenging mission—for humans to visit the depths and see what the ocean bottom was like firsthand, following in the bubbles of William Beebe, who championed the midwaters in his bathysphere.
But was Thomson merely lucky in his choice of sites, or was the entire deep sea similarly full of life? Would that life comprise the same kinds of species, or would it be completely different? And where were all those living fossils?
Edward Forbes started the initial push to dredge life from the bottom, but he gave up early, declaring an azoic, or no-life, zone below a depth of 1,800 feet (550 m). Taking up the quest in the 1850s (and later named to Forbes’ chair of natural history at the University of Edinburgh), Charles Wyville Thomson (later Sir Charles) became convinced that there was life on the bottom and, after reading Darwin, that some of this life might even be ancient. He and others of his time wondered whether the deep sea might be a refuge for extinct forms, the so-called living fossils.
Thomson traveled to see Norwegian biologist Michael Sars and his amazing collection of marine animals dredged from the 1,800-foot-deep (550 m) Lofoten Fjord. Most notable was a primitive kind of echinoderm—the phylum, or taxonomic category, that contains starfish, brittle stars, sea urchins and sea cucumbers—a crinoid, or sea lily (class Crinoidea), then known only from 120-million-year-old fossils from the early Cretaceous period. The stalked sea lily (Rhizocrinus lofotensis), sometimes up to three feet (1 m) tall, looked more like a plant than a starfish, but it was actually an animal that kept itself anchored to the ooze and obtained food by sweeping its “fronds” through the water.
The sea lily, and the promise of additional discoveries, enabled Thomson and his friend W. B. Carpenter to enlist the support of the Royal Navy. Through The Royal Society of London, they explored the deep waters north and west of the British Isles and extended south to the Iberian Peninsula. Annual summer expeditions began in 1868 aboard the HMS Lightning, followed in successive years by the HMS Porcupine and the HMS Shearwater. Penetrating the bottom ooze at depths extending down to 14,610 feet (4,450 m)—nearly 2¾ miles (4.5 km)—the crew pulled up dredge after dredge containing evidence of life. For the most part, they found skeletons of animals that had fallen from the surface waters, but in July 1869, at the edge of what would come to be called the Porcupine Abyssal Plain, southwest of Ireland—the greatest depth they reached—the ship’s creaking 12-horsepower engine helped haul up the deepest prize: various species of mollusks, annelid worms, sponges and echinoderms, true inhabitants of the deep.
Thomson had rendered lifeless the idea of Forbes’ azoic zone. But was Thomson merely lucky in his choice of sites, or was the entire deep sea similarly full of life? Would that life comprise the same kinds of species, or would it be completely different? And where were all those living fossils?
Keen to answer these and other questions, Thomson plotted a multidisciplinary round-the-world cruise. Besides all the life he had found, he had taken temperature readings at various depths that stirred arguments about ocean circulation and the possible role of the deep sea. Returning to enlist support, Thomson found the Royal Navy eager to survey the deep before laying submarine telegraph cables. With the Royal Navy and broad scientific support, Thomson was able to organize what became a 3½-year cruise on the HMS Challenger. From 1872 to 1876, the ship logged 68,930 miles (110,930 km), performed some 300 dredgings and trawls, and pulled up an estimated 13,000 plant and animal species from the deep, including nearly 5,000 new species.
In the early days, the men on board the ship gathered round to see what was hauled up, wondering what new monsters might appear. But soon the tedium of the endless stations, where the dredge would be set down, only to take hours to haul up, was closer to leading to mutiny than anything else. Ever the engaged naturalist, Thomson sustained his curiosity throughout. Occasionally, bizarre bioluminescent treasures were snared by the dredges, yet no bona fide sea monster or dinosaurlike living fossil appeared, with one possible exception: a small Spirula squid, considered a missing link between ancient and modern squid.
Thomson found little to support the great 19th-century idea of fossil sea monsters. Other researchers would later find a few “living deep-sea fossils,” such as the turn-of-the-century vampire squid described earlier and the coelacanth discovered off South Africa in 1938 and thought to have been extinct for 70 million years. These were enough to keep the idea alive, barely. Fossils, living or dead, were just not as prevalent in the sea as had been hoped or believed. In fact, the diversity of the deep sea was somewhat of a disappointment to Thomson and others who took part in the Challenger Expedition, despite the large number of specimens they collected. Only later would they realize that their method of dredging was largely to blame. When the meshes became finer in the 1960s and the techniques for capturing life at depth more refined, scientists were able to pull up many more species.
A turning point in oceanography, the Challenger Expedition took soundings throughout the ocean, making possible the first glimpse of the shape and depths of the world ocean basin. It discovered the midocean ridge in the North Atlantic, part of the world’s longest mountain range, and helped define the location of the world ocean’s major trenches, the deepest places on Earth. It actually found the famous Challenger Deep—the deep part of the Mariana Trench, near Guam—and pulled up a bit of mud just 50 miles (80 km) from the very deepest spot. Thomson spent a good part of the rest of his life examining the findings of the Challenger Expedition, writing up and editing 34 large volumes on the biology alone, as well as elaborating on many of the other discoveries.
The Challenger Expedition paved the way for American and European oceanographic expeditions. At the advent of the 20th century, Prince Albert of Monaco trawled at 20,000 feet (6,000 m) on the abyssal plains and pulled up brittle stars, a fish and several other small organisms; for many years, he held the record for creatures found at depth.
Not until the Danish Deep Sea Expedition aboard the Galathea (1950–52) were the trenches finally studied. The depths of the Philippine Trench were sampled with a dredge that descended 33,400 feet (10,180 m). While not the very bottom of the sea, it was within 1,400 feet (430 m) of it and was deep into the hadal zone. The term “hadal” was, in fact, coined in the wake of this expedition by oceanographer and zoologist Anton F. Bruun of Copenhagen.
Galathea’s dredge brought up sea anemones, mollusks, bristle, or polychaete, worms and plenty of sea cucumbers—essentially mud-eaters, creatures that ingest mud for the food it contains. These same groups of animals had been found 80 years earlier by the Challenger Expedition, although the species turned out to be different. Trench species were mainly echinoderms, on the small side, not monsters and not fish. Although dredges are unreliable for picking up fish at depth, it would appear that the number (biomass) and species (diversity) of fish decline in the trenches.
The Galathea had gone deep with its dredge but had not reached the very deepest part of the trenches. In 1951, the same year the Galathea did its deepest work, the HMS Challenger II—a British ship carrying the name of its legendary predecessor—used sound waves to measure the bottom in the Mariana Trench in a portion of the Philippine Trench southwest of Guam. Called Challenger Deep, the depth was recorded at 35,760 feet (10,900 m). The honor of reaching the deepest realm on Earth, of actually coming into contact with it, would be saved for a manned descent.
About the time that William Beebe was preparing to descend to the depths of the midwaters, Swiss physicist and inventor Auguste Piccard was breaking records with his high-altitude balloon attached to an aluminum gondola, climbing to a chilly height of more than 10 miles (16 km) while breathing pressurized oxygen from a tank. But Piccard was also contemplating the deep. Fresh from his triumphs in the upper atmosphere, Piccard met Beebe at the 1933 Chicago World’s Fair and saw the bathysphere designed by Otis Barton. Over the next quarter-century, Piccard worked on designing and building a small manned vehicle to explore the depths—something truly worthy of Jules Verne and his Twenty Thousand Leagues Under the Sea. Piccard liked the idea of the sturdy, pressure-resistant steel sphere with which Beebe and Barton had had success. Piccard designed his submersible a little larger, at seven feet (2 m), and much stronger to withstand greater depths, complete with thicker steel walls and portholes of a then experimental plastic called Plexiglas. His major advance, however, was eliminating the tether to the ship. Piccard’s invention would be a real underwater vehicle. Adapting his ideas about balloons to deep-sea vehicles, he designed a craft with multiple chambers in large tanks that could be filled with air, seawater or gasoline, which was lighter than seawater. He also had a compartment for iron ballast, in pellet form, that could be dropped, as needed, to rise or return to the surface.
Piccard called his invention the bathyscaphe. It was not just a “deep sphere,” in the literal Greek translation of Beebe and Barton’s bathysphere, but a deep boat. Once it was at the desired depth level, the bathyscaphe relied on propellers for forward movement. The vehicle turned out to be slow-moving and difficult to maneuver, and innumerable test runs only minimally improved the performance.
The first bathyscaphe prototype, funded by the Belgian government, was tested in 1948. It carried no passengers and met with mixed success. Thereafter, sponsorship for improved models was taken over by various Swiss patrons and by the city of Trieste, Italy. In 1953, the newly named Trieste, twice as long as the original bathyscaphe, was launched off Naples. Piccard, now nearly 70 years old, was joined by his 31-year-old son Jacques, and the pair descended two miles (3 km), bumping down into sediment and slowly sinking. Going nearly four times as deep as Beebe and Barton had two decades earlier, the Piccards broke all records, but their celebratory mood was muted when they could see no life outside the craft. Part of the problem was that the Trieste was mired in the mud. Even with the ship’s powerful outside lights, they could see nothing moving. Had they frightened everything away?
To some extent, perhaps they had, but the Mediterranean is also somewhat less densely populated by deep-sea life, as other pioneer researchers back to Forbes and even Aristotle had discovered. In any case, the Piccards had to find new sponsors. In 1957, the U.S. Navy commissioned 15 dives (later increased to 26) in the Mediterranean off Naples. Jacques Piccard worked as the pilot, escorting naval scientists one by one to make observations and do experiments. Although the primary work was communications- and weapons-oriented for Cold War defense, they did find plenty of bioluminescent fish in the midwaters and considerable life in the depths.
Pleased with the work, the U.S. Navy purchased Trieste from the Piccards, along with the services of Jacques Piccard. Part of the deal was that the Navy would build a new Trieste, with thicker steel walls, smaller, stronger portholes and other innovations that would allow it to descend to even deeper seas, to scale the deep-ocean trenches and visit the very bottom of the world ocean.
Piccard, who had kept alive his and his father’s dream to go to the absolute bottom of the sea, finally had his big chance, and the deep pockets of the Cold War U.S. Navy would pay for it. His father Auguste, who had spent years designing the original craft and accompanying his son on dives, was then in his late 70s, but he followed his son’s exploits from the other side of the world, in Switzerland.
After a few test runs off San Diego in 1959, the craft and personnel were transported across the Pacific to Guam, the U.S. base nearest to Challenger Deep, in the Mariana Trench, the deepest trench in the ocean.
On the overcast early morning of January 23, 1960, Piccard was aboard the USS Wandank, riding the high swells of the open Pacific some 250 miles (400 km) southwest of Guam, more than 1,000 miles (1,600 km) east of the Philippines. Piccard stood watching and listening as a nearby survey ship dropped hundreds of TNT charges to try to pinpoint the deepest spot in Challenger Deep. He wondered whether it was going to be too rough to board the Trieste.
Minutes later, however, Piccard and Navy Lieutenant Don Walsh scrambled aboard, sealing the hatch behind them. The excitement of the launch died quickly as the bathyscaphe dropped from the blue waters to the black—and then to black and more black. Moving at an average speed of just 1½ miles per hour (2.4 km/h) through an ever-tightening vise of the most intense pressure ever experienced by a human craft, the Trieste took nearly five hours to reach the bottom.
At 32,400 feet (9,875 m), Piccard and Walsh heard a strong, muffled explosion and thought they might have hit bottom or, worse, the steep walls of the trench. The Trieste shuddered, and Piccard, if not Walsh, wondered briefly whether a terrible implosion was imminent. But nothing happened, and they continued their descent. Finally, the 150-ton (136,000 kg) Trieste touched down on the bottom, and like two astronauts landing on another world, Piccard and Walsh gazed out through the portholes. On the other side of the glass, their spotlight lit up the netherworld. It was another world. “The bottom appeared light and clear,” wrote Piccard, “a waste of snuff-colored ooze.”
So this was what it looked like at 35,814 feet (10,916 m)—6.8 miles (10.9 km)—below the surface, with 16,000 pounds (7,260 kg) of pressure being exerted on every square inch of the Trieste. They had just gone where no human had gone before, but what Piccard and Walsh actually glimpsed from the portholes was somewhat anticlimactic. There was no King Neptune to greet them. And unlike the astronauts on the manned Moon landing that would happen at the end of the same decade, they could not step out of their craft onto the surface of this new world, plant a flag and say something memorable. There were no hellish monsters at the hadal depths. In fact, the signs of life were minimal, though notable.
Piccard thought he saw a flatfish, about a foot (30 cm) long, lying on the bottom. Most surprising, it had eyes. Blinded by a spotlight thousands of times brighter than anything it had ever experienced in its recent evolutionary history, much less its life, the flatfish slowly swam off into the black, never to be seen again, certainly not by humans and probably not by any other creature, due to the rarity of eyes and the absence of light or even bioluminescence at this absolute depth. Piccard also spotted a large red shrimp. Yet no photographs were taken. In what must surely rank near the top of the all-time missed opportunities, the pair carried no camera on board.
Piccard and Walsh shook hands to mark their amazing feat, then managed to make excited voice contact with the surface, relaying their depth and estimated time of arrival. With the temperature measuring only 50 degrees F (10°C) inside and 36.5 degrees F (2.5°C) in the water, they both felt chilled. Twenty minutes after reaching the bottom, they began their ascent. After another 3½ hours, hungry for fresh air and eager to get out of their underwater “elevator,” they broke the rough surface and struggled to emerge from their cramped quarters. Two Navy jets tipped their wings overhead in salute, and two photographers snapped photos. To the bottom of the world and back, all in a day’s work. It had taken decades of planning and dreaming. Nearly seven years earlier, in 1953, mountaineers had climbed to the top of Mount Everest; in 1957, astronauts had managed to orbit the Earth. Now, finally, humans had reached the bottom of the sea.
It was untrue that the bathyscaphe had started bending in on itself, as some reports claimed, but as expected, it did shrink by a few inches under pressure, producing a flurry of paint flecks from time to time in deeper waters. Much more worrisome, however, was the fact that the plastic window on the antechamber, which was the escape route, had cracked in various places because of the different rates of contraction of the plastic and the surrounding metal. It was not caving in, but it was a concern and had caused the muffled explosion Piccard and Walsh had heard on their descent. After the deep dive, Navy engineers decided that the Trieste was unsafe and would be unable to withstand pressures of 16,000 pounds per square inch again. By 1963, the record-breaking little vessel was retired.
Had the Trieste caved in, it would have produced an awesome implosion, propelling and scattering material for a great distance in all directions. There would have been no rescue attempt or even a cleanup. No other vehicle, manned or unmanned, could reach anywhere near that depth.
Since 1960, the U.S. Navy has not built any new submersibles capable of scaling the hadal canyons to the bottom. None of the Cold War nuclear-powered submarines can travel in the deep trenches, though absolute-depth capability remains classified information. Kaikō, a Japanese unmanned remotely operated vehicle (ROV), had hadal-depth capability, and in March 1995, it ventured to the bottom of Challenger Deep to a depth of 35,797 feet (10,911 m), just 17 feet (5 m) shy of the Trieste’s record, although still within the margin of error. Kaikō made two subsequent journeys to Challenger Deep, collecting many microbes and other specimens, before it was lost at sea in a typhoon in 2003. In 2009, Nereus, a Woods Hole Oceanographic Institution ROV, also reached close to the deepest recorded depth but without human occupants.
It would be left to private enterprise, so to speak, to help inspire, fund and try to match Piccard and Walsh’s journey to Challenger Deep. This first solo attempt to reach the bottom of the sea would usher in a new century of deep-ocean exploration. Space travel was being taken over by private companies driven by the vision of a few individuals such as Richard Branson, and deep-sea exploration looked to be developing along similar lines—with a twist. The deep sea was about to be invaded by a Canadian-born filmmaker with deep Hollywood connections.
The route that James Cameron took to the bottom of the sea was far from direct—or straight down. Cameron flirted with physics classes as a student. Later, as an adult, he liked to experiment with special-effects technologies related to underwater filming. More broadly, he explored science fiction script ideas in such films as The Terminator, Aliens and The Abyss. He made documentaries on the deep. He earned an enormous amount of money, some years as the top earner in Hollywood, enough that he could take his time to shoot several of the biggest-budget films the way he wanted and even to finance an excursion to the deep. As a director and producer, he could be a tyrant and a perfectionist, and a few colleagues called him the Captain Bligh of filmmaking. None of these traits was perhaps ideal, given the level of cooperation needed to undertake a successful journey to the Mariana Trench, although perfectionism and attention to detail in outfitting and testing the sub would help ensure its occupant’s survival.
When James Cameron accepted Best Director and Best Picture Oscars for Titanic, the 1997 romantic disaster epic that became the first film to earn a billion dollars, he famously proclaimed, “I’m the king of the world!” It was a grand boast, a reprisal of a line from the movie spoken by the Leonardo DiCaprio character Jack in a moment of romantic largesse. The king of the world was now aiming to be king of the sea.
A modern-day William Beebe, Cameron decided early on that his journey to the Mariana Trench would be a film documentary, and he engaged the ideal partner in the National Geographic Society. The Society had the television platform, the lustrous history of exploration, the PR muscle and the technical reinforcement that Cameron required for such a complex expedition. Cameron started on his mission in 2005. At the time, he was working on other projects, including the long-awaited realization of his sci-fi vision Avatar.
After Avatar’s worldwide release in 2009, Cameron turned his full energies to finishing his preparations for the testing of Deepsea Challenger, the one-person submarine that he had codesigned, the vehicle that would take him to the bottom. It was not a government-issue sub backed by some powerful navy, but as Cameron put it in his 2013 National Geographic article, it was a “little green torpedo … built privately, in a commercial space sandwiched between a plumbing-supply wholesaler and a plywood shop in the suburbs of Sydney, Australia.” In addition to the sub, Cameron had helped design tiny high-definition 3-D cameras in titanium housings to take close-ups of what he saw. He also brought along two refrigerator-sized unmanned vehicles to dive with the sub and sample the sediment, seawater and species near the bottom.
The name of the sub, Deepsea Challenger, came from the original Challenger Expedition by way of Challenger Deep, the deepest part of the Mariana Trench, which was Cameron’s goal. Cameron was, indeed, challenging the deep sea. Weighing in at 12 tons (10,900 kg), the 24-foot-long (7.3 m) lime-green sub had yet to be tested under ocean conditions. Cameron had made more than 80 deep submarine dives, 33 of them to the RMS Titanic, but this new vehicle was going to a depth far beyond any he had ever attempted. He needed to know how to pilot it and what to do if things went horribly wrong.
Twelve small thrusters would move the sub once it reached the bottom—six each for vertical and horizontal control. But more important than the thrusters and all the other high-tech systems on the vehicle were the weights. The sub was equipped with steel weights of 600 to more than 1,000 pounds (270–450 kg). These weights would take the sub down to the bottom at the appropriate speed; their subsequent release would bring the sub back to the surface. There was considerable concern about backup systems that would guarantee the weights would drop off, and Cameron and his team had “designed about eight different ways” to make sure they would.
Fitting into the cockpit was not easy. It was only 43 inches (110 cm) in diameter, and Cameron himself was 6 feet 2 inches (188 cm) tall. He lowered himself down through the 400-pound (180 kg) hatch, which was about the size of a manhole cover, and assumed a hunched, knees-up sitting position, bending his head along the curve of the hull, his bare feet pressing against the warm steel.
The mother ship, Mermaid Sapphire, rocked in the swells but held position at 11°22' N, 142°35' E, directly above the deepest pit in the sea. Showtime.
A lot was going through Cameron’s mind in the hours after midnight on March 26, 2012, as he and his team began four hours of checks in preparation for the final descent. Two key members of the expedition had died in a helicopter crash only weeks before. During test dives off Papua New Guinea with the 3-D cameras, the entire electrical system had gone on the blink, the carbon dioxide scrubber had fallen off the cockpit wall into Cameron’s lap and there were software glitches. Plenty of rough weather and missed deadlines might have caused the expedition to be postponed indefinitely. But the test dives to ever deeper trenches had already provided valuable scientific data, and the sub’s traps had scooped up gigantic white-shell amphipods that had stripped the bait—a whole raw chicken—to the bone. Hoping to get lucky, they persisted.
Shortly after 5 a.m., Cameron gave the signal and the shipboard team let the sub drop—like a stone. Cameron seemed outwardly calm but confessed in his 2013 National Geographic article, “I am wrapped in the sub, a part of it and it a part of me, an extension of my ideas and dreams.” Cameron glanced at the dials: 500 feet (150 m) per minute. Is there too much weight on this? The sub was designed to go down and back fast to allow more time on the bottom, but was this too fast?
The external temperature fell from 85 degrees F (29°C) at the surface to a near freezing 35 degrees F (1.7°C) as the sub descended into the black. Cameron’s bare feet turned cold against the steel, and he struggled to pull on his neoprene booties. Next, he slipped on a knitted hat, à la Jacques Cousteau, to insulate his head as it rested against the steel.
Despite the minor discomfort of being crammed into what some might consider not much more than a cold coffin, Cameron felt at home. “Snug” was the word he used. He had experienced enough submarine travel that the space felt familiar. The cockpit had four video screens that occupied his field of vision; three displayed views from the external cameras, and one was a touch-screen instrument panel. It vaguely resembled a compact mixing studio or mobile editing suite. For Cameron, that was another kind of home.
Except for the off-and-on hiss of the oxygen solenoid, all was quiet. Cameron strained to look into the blackness, but all he could see was plankton racing past, illuminated by the sub’s powerful LED searchlights, part of the expedition’s 3-D film equipment. Having gone through his checklist, Cameron thought about the intense pressure building outside the sub and what would happen if the vehicle were to spring a leak. “If Deepsea Challenger’s hull fails, I won’t feel a thing,” he wrote. “It’ll be a CUT TO BLACK.”
At 27,000 feet (8,230 m), 90 minutes into the descent, Cameron began to drop some of the ballast. From the initial 3.5 knots, he slowed to 2.8 knots, then 2.5 knots. As he neared the bottom at 35,600 feet (10,850 m), he used the thrusters to limit the speed to half a knot.
The altimeter showed the bottom to be 150 feet (45 m) below. He turned on all the lights and started the cameras rolling.
At 60 feet (18 m) away, he observed a “ghostly glow” reflecting off the bottom. He hit the vertical thrusters, braking ever so delicately. A faint downwash seemed to come from just beneath the vehicle.
Cameron aimed the spotlight across the seafloor. It burned a hole through the blackness, the water surprisingly clear. Looking all around, the filmmaker could see nothing. He found the bottom to be “utterly uniform, devoid of any character but the absence of character,” different from seafloors he had seen on all his previous dives.
Within seconds, he touched down at 35,756 feet (10,898 m). The vehicle sank about four inches (10 cm) into the ooze, and the sediment drifted up like a fog machine. He was 23 miles (37 km) east of where Walsh and Piccard had landed. It was 7:46 a.m., a mere 2½ hours since he had begun his journey to the bottom of the sea.
The Mermaid Sapphire, nearly seven miles (11 km) above, made contact. Cameron acknowledged that he’d reached the bottom and all was fine. After a shared moment of relief and celebration, tinged with warmth for all who had worked to make this moment possible, Cameron got busy, knowing he would have just five hours on the bottom to explore, collect samples and make the most of this extraordinary opportunity. First, he deployed the external arm from the science door to take a sediment core sample. But only minutes after bringing the sample on board, the hydraulic system started leaking, the arm and the science door malfunctioning. Unable to take any more samples, Cameron started inching across the hadal bottom. He later said it was like driving on newly fallen snow, with the odd amphipod floating past like a wayward snowflake.
Cameron turned to look out the window and contemplate the “stillness of this alien place.” Chugging along, he was shocked that he could see so few signs of life, beyond the snowy amphipods. He felt as if he had gone to a place beyond the very limits of life itself. He photographed a “gelatinous blob” on the bottom and a dark scar that might have been the home of a sediment worm. The blob turned out to be a giant single-cell amoeba, a so-called xenophyophore. He observed what looked to be a new squid worm species, a worm that takes on the appearance of a squid with modified feeding appendages. And there were sea cucumbers everywhere, including a species unlike anything he’d seen before. No species can be identified as new, however, unless it can be collected and examined. Still, Cameron was banking on the single sediment sample he had taken, hoping it would reveal something more.
As the sub slowly headed north, Cameron moved gently up and along the ridges of a slope, looking for rocky outcroppings with signs of life. Nothing. He was now a mile away from his landing place and just under three hours into the expedition. He began to worry about his batteries running low; the compass was blinking off and on. Then the sonar died. When two of the starboard thrusters failed, Cameron found it hard to control the sub. The extreme pressure was taking its toll. He pressed on, but when the sub abruptly lurched to the right, he discovered that his last starboard thruster was gone. Reduced to turning in circles and unable to take samples, Cameron decided it was time to abort. He called up to the Mermaid Sapphire. He was more than two hours short of his planned stay on the bottom, but it was time to head for home.
Flipping the switch to drop the weights, Cameron shot up suddenly and felt a sense of relief that the mechanism worked. The bottom dropped away, and the speed quickly built up to 6 knots, the fastest the sub had ever travelled. In less than 90 minutes, Cameron reached the surface, opened the hatch and smiled at his team.
Cameron was now officially the “king of the underwater world.” A touching moment occurred shortly after his arrival back aboard the Mermaid Sapphire. Retired U.S. Navy Captain Don Walsh, who had descended to Challenger Deep in 1960, was there to congratulate him and “welcome him to the club.” After Piccard’s death, Walsh was the only man alive to have visited the bottom of the ocean. Now there was one more.
In fact, though rarely reported, neither Cameron nor Walsh and Piccard had actually reached the very bottom of the Mariana Trench. In 1957, the Soviet vessel Vityaz recorded a depth of 36,201 feet (11,034 m), which was dubbed the Mariana Hollow. In 2009, however, in perhaps the most definitive measurement to date, the R/V Kilo Moana, mother ship of the Nereus ROV, used a sonar multibeam bathymetry system developed for deep-water mapping to record a spot in the trench that is 35,994 feet (10,971 m) deep. The accuracy of this measurement is to within plus or minus 72 feet (22 m). This may be the most reliable estimate of the deepest part of the ocean. If so, no human has made it there yet—close, but not quite.
Yet even with these explorations of the hadal depths, the belief has persisted that the deep trenches and the abyssal plains harbor a “reduced” monotonous fauna. Yes, there is life, but it appears to be fairly similar from place to place. Compared with the rich intertidal zones and the surface of the sea, the bottom seems to be something of a muddy desert populated by little more than sea cucumbers and worms. Despite efforts to find diversity and prove otherwise, the Challenger Expedition (1872–76) had “established” this as “fact,” and Piccard and Walsh’s dive, as well as Cameron’s, had not dislodged that overall impression. And although Cameron took pictures, he was unable to bring back more than one sample of the ooze.
In the mid-1960s, however, five years after Piccard and Walsh visited Challenger Deep and nearly 50 years before Cameron’s expedition, this misconception was challenged. Biologists Robert Hessler and Howard Sanders of the Woods Hole Oceanographic Institution did extensive dredging and trawling in the deep-sea regions between Cape Cod and Bermuda, and what they found surprised everyone.
Their “epibenthic sled” was able to capture animals just above and below the ocean bottom, as well as on the bottom itself. Also, the mesh was much finer. Hessler and Sanders found literally hundreds of species where one or two were thought to exist. There were tens of thousands of species, not a few hundred. Although the number of species declined as the sled went ever deeper, the number was much higher and the diversity greater than had been imagined.
Hessler and Sanders went only as far as the abyssal plains. Some researchers believe that the number of individuals and the diversity of species, as well as microbes, in the hadal zone trenches may be greater than on many parts of the abyssal plains, which would reverse the general trend of declining diversity the deeper you go. The thinking is that since trenches are mainly located close to land and beneath productive surface waters, the rain of nutrients, including dead bodies from the surface, is greater than it is farther out to sea above the abyssal plains. After the nutrients fall, they become “trapped” in the trenches.
Life-forms do vary from trench to trench. Deep-sea biologists have found different species of sea cucumbers and other mud-eaters in different trenches. This makes sense, as the trenches are deep holes or valleys that function like islands separated from one another by considerable stretches of abyssal hills and plains. The result is reproductive isolation—one of the evolutionary processes that create new species.
The more scientists explore the abyssal plains and hadal depths, the more they find new species of echinoderms, the phylum that includes starfish, sea anemones and sea cucumbers. To be fair, there are more echinoderm taxonomists than taxonomists for other groups. The bottom megafauna at hadal and abyssal depths is composed largely of echinoderms. To our iMonstercam, it seems a gray desert, the odd sea pen standing nearly a foot (30 cm) high, like a feather stuck in the ground. A little larger, at a foot (30 cm) or more long, the brisingid starfish, with its curved-up arms, resembles a sun-beached headless skeleton, or at least its rib cage. There are also cnidarians, such as Chitoanthis abyssorum, and mollusks. One well-adapted fish uses its fins to stand on the bottom. The tripod fish (Bathypterois sp.) is negatively buoyant, lacking a swim bladder or other means of buoyancy. But more than anything, there are the holothurians, or sea cucumbers, on the bottom. And they are not one species but many.
The very bottom is, in many ways, the “kingdom of the sea cucumber” or, for those less romantically inclined, the kingdom of the mud-eaters. These so-called holothurians feel at home on the seafloor and have diversified into at least 900 species. Many are, indeed, cucumber-shaped, ambling across the bottom at a few yards per hour, their multiple feetlike protrusions moving them along in a rhythmic swaying motion.
Headless creatures equipped to inch along the bottom or to launch themselves into the water column, sea cucumbers often travel in great herds, “galloping” across the abyssal plains and the bottom of the hadal trenches. Other sea cucumbers look more like mini flying saucers except when they move, undulating over the seafloor like other bottom flatfish adapted to look like the bottom topography. Usually gray, brown, black or olive green, sea cucumbers can grow six feet (2 m) or more in length. The longest are found in shallower waters, where they move on or just above the seafloor like headless snakes. The hadal sea cucumbers are smaller, some little more than an inch (2.5 cm) long, and are more groveling—true mud sloshers. Looking closely, it is possible to discern the front end—on the rare occasion when it’s not buried in the mud. There are no eyes, but feathered tentacles surround the mouth, and in some species, the tentacles are periodically inserted into the mouth after extracting juicy nutrients from the mud.
The sea cucumber has many strange habits. For starters, it breathes through its anus. When you’re a plodding, toothless creature that must take urgent evasive action, desperate measures are sometimes required.
The sea cucumber has many strange habits. For starters, it breathes through its anus. Like its cousin starfish, the sea cucumber can regenerate certain body parts if needed, such as the digestive tract, and is able to expel its guts and other internal organs through its rear end, then grow a new set in the space of a few weeks. This behavior may be a way of distracting or frightening off a potential predator as the sea cucumber makes its getaway. When you’re a plodding, toothless creature that must take urgent evasive action, desperate measures are sometimes required.
The prevalence of sea cucumbers on the ocean bottom and their variety of shapes and sizes have led some biologists to suggest that Jacques Piccard may have seen a sea cucumber, not a flatfish, when the Trieste set down on the bottom of Challenger Deep. Perhaps the bottom sediment was so disturbed by the landing of the bathyscaphe that Piccard didn’t get a clear view. These same biologists are fond of pointing out that Piccard was not a biologist, and neither is James Cameron, though Cameron at least had camera documentation of what he encountered. In Piccard’s defense, he had more experience in the deep than any biologist or any other person alive at the time, but it’s also true that fish have not been found at that depth on any other trip to Challenger Deep since, whether by remote or manned vehicle.
The sea cucumber is a fantastic, fascinating creature, worthy of curiosity and understanding, although it is hardly a monster. Or is it?
From its perch on the seafloor, the iMonstercam turns 360 degrees, and from every angle, sea cucumbers are slowly but steadily approaching to investigate this alien presence. Strange mouths open and close all around, coming ever closer, looming above the small camera. One sea cucumber startles another, whose guts promptly shoot out. And then, in the commotion, it happens. The largest sea cucumber nudges the device, and the feathered tentacles around its mouth tickle the lens. We are too close for comfort. Then everything goes dark. Nothing down here on the bottom escapes attention for long. And we find ourselves in the middle of a biology lesson that shows how everything is investigated, recycled and almost, but not quite, devoured.
Of course, there is not much nutritional value in the species iMonstercam, and the sea cucumber soon goes back to filtering mud. But anything that arrives on the bottom from above, particularly anything different, is promptly filtered for any nutritional value it might contain. Had we baited the camera, we could have expected tiny scavenging amphipods to descend en masse as well as various fish, such as grenadier fish, all drawn to the smell of food in the water. With its flashing on-off light, its huge eye lens and its partly silver-white and partly black coloring, the iMonstercam arguably shares something of the deep-sea creature morphology. Much stranger deep-sea creatures exist in the land of the mud-eaters, where the sea cucumber ever roams.
Indeed, the sea cucumber may be the king of the deep: the once and future resident of this land, thriving in the hadal trenches and slopes and on the abyssal plains.
A postscript to Cameron’s 2012 expedition: The sediment he collected was, indeed, full of microbes—bacteria, archaeans and more. A 2013 paper in Nature Geoscience by Ronnie Glud and his colleagues compared the Challenger Deep microbes with those in a nearby 19,685-foot-deep (6,000 m) site. They found twice as much microbial activity in the sediments of the Mariana Trench as in the shallower site, and there was an elevated rate of deposition of organic matter, with oxygen consumption occurring twice as fast as in the shallower site. Perhaps the microbes are the true kings of the deep sea?
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