Boil line Located immediately downstream of a hole (see definition following), the point at which current begins to pass downstream again instead of rushing upstream into the hole.
Boof To launch over and off of a rock at the top lip of a drop. A successful boof lifts the bow so that the angle of the boat is more shallow than the angle of the water falling off the drop.
Bow The forward end of a canoe or kayak.
Brace Paddle stroke used to prevent the boat from flipping over.
Breaking wave A wave that intermittently curls back on itself, falling upstream.
Bypass A channel cut across a meander that creates an island or oxbow lake.
Chock stone A stone onto which the current flowing over a falls lands.
Chute A channel between obstructions that has faster current than the surrounding water.
Curler A wave with a top that is curled over onto the face of the wave.
Deadfall Trees or brush that have fallen into a stream, totally or partially obstructing it.
Decked boat A kayak (usually) or canoe that is completely enclosed and fitted with a spray skirt that keeps the hull from filling with water.
Downstream V A river feature often marking the best route through obstacles, with the point of the V facing downstream. Formed by the eddy lines resulting from two obstacles bracketing a faster channel of water, or by turbulent water bracketing a smooth tongue.
Drop-and-pool A river characterized by rapids separated with long, placid stretches. The rapids act as natural dams that still the current preceding the drop.
Eddy The water downstream of an obstruction in the current or below a riverbend. The water in the eddy may be relatively calm or boiling, and will flow upstream.
Eddy line The boundary at the edge of an eddy separating two currents of different velocity and direction.
Eddy out To exit the downstream current into an eddy.
Eddy turn Maneuver used to enter or exit an eddy.
Ferry A maneuver for moving laterally across a stream, executed facing up- or downstream.
Flood stage The point at which a river is out of its banks. The level associated with flood stage is location specific and depends on the depth of the river bed, height of the banks, and flow.
Gradient A river’s change in altitude over a fixed distance, usually expressed in feet per mile.
Hair Turbulent, foamy white water.
Haystack A pyramid-shaped standing wave caused by deceleration of current from underwater resistance, commonly found at the end of a chute where the faster current collides with the slower-moving water pooled below the rapid.
Hole A river feature in which water moves over an obstacle with sufficient flow and velocity to create a wave that violently and continuously breaks (recirculates) upstream against its face.
Hydraulic General term for souse holes and holes.
Keeper Any hole that is difficult to exit. Can take the form of a hole whose right and left edges curve upstream and fold back into itself, or a very large hole whose boil line is more than a boat length downstream.
Ledge The exposed edge of a rock stratum that acts as a low, natural dam, creating a falls or rapid as current passes over it.
Line A viable route through a rapid.
Low-head dam A usually man-made obstacle that laterally spans a river from the left to the right bank, creating a pool upstream and a keeper hydraulic immediately below. Grimly referred to as the “perfect killing machine” for its lack of exit points once a boater is caught in the hydraulic.
Meander A large loop in a river’s path through a wide floodplain.
Oxbow A U-shaped lake formed when a river’s meander is bypassed by the main channel.
Peel out A maneuver for exiting an eddy and quickly entering the downstream current.
Pencil in When a boat pierces the water below a drop in a vertical position.
PFD Personal flotation device; better term for “lifejacket.” The U.S. Coast Guard recognizes five classes of PFDs. The American Canoe Association recommends Coast Guard–approved Class III PFDs.
Pile The frothy white water on top of a wave or in a hole.
Pillow Bulge on the surface of a river created by water piling up against an underwater obstruction, usually a rock.
Pinning When an object (usually a boat) is pushed onto an obstacle (usually a rock) and held there forcefully by the pressure of the current.
Pool A section of river where the prevailing current has been stilled and the water is usually deep and quiet.
Portage To avoid an obstacle, hazard, or rapid by exiting the river, carrying boat and gear downstream, and reentering the river below the obstacle.
Pothole Formed by erosion, a depression in the river bed at the base of a steep drop.
Pour-over A sticky hole formed by water flowing over an abrupt drop.
Punch To approach and pass through a hole aggressively, boat perpendicular to the hole, to reach the current moving downstream beyond the boil line.
Rapids Portion of a river where there is appreciable turbulence usually accompanied by obstacles.
Riffles Slight turbulence with or without a few rocks tossed in; usually found where current is swift and very shallow.
River left The left side of the river as determined when facing downstream.
River right The right side of the river as determined when facing downstream.
Rock garden Rapids that have many exposed or partially submerged rocks, necessitating intricate and technical maneuvering.
Roll The technique of righting a capsized kayak or canoe with the paddler remaining in the paddling position.
Scout To evaluate a rapid (either from the shore or while your boat is in an eddy) to decide whether or not to run it, or to facilitate selection of a suitable route through it.
Shuttle Using vehicles to transport people and boats on land between river-access points prior to or after a run.
Sieve A hazard formed by channels of swift water flowing through menacingly tight spaces between and underneath boulders, usually accompanied by undercuts. Water can flow freely through, but debris and paddlers are easily pinned under water by the forceful currents.
Slide rapid An elongated ledge that descends or slopes gradually rather than abruptly, usually covered by shallow water.
Sneak An alternative route through a rapid that avoids the main flow. Usually, but not always, an easier route than the main channel.
Souse hole See Hole.
Spray skirt A hemmed piece of neoprene or nylon clothing that resembles a short skirt, having an elastic hem fitting around the boater’s waist and an elastic hem fitting around the cockpit of a decked boat.
Standing wave A wave that does not move in relation to the river bed. See Haystack.
Stern The rear end of a canoe or Kayak.
Strainer Branches, trees, or vegetation that is partially or totally submerged in a river’s current. Serious hazards for paddlers, strainers allow only water to pass through freely. The current will pull anything else down, plastering it into place, similar to the action of a kitchen colander.
Surfing The technique of situating your boat on the upstream face of a wave.
Swamp To fill a canoe or kayak with water.
Tongue See Chute.
Undercut rock A hazard in which a river has eroded a boulder below the surface of the water, creating a cavity with potential for entrapment not visible above the surface.