Drop - Used to refer to any sudden fall in height on a river, from a foot or two up to around 3m (where drops tend to merge into "falls"). A short, well-defined rapid or section of a rapid. Named for the abrupt drop in elevation between the top and bottom of the rapid.

Eddy - Eddies are areas of still or reverse (upstream) moving water. They are formed on rivers when the water comes up against an obstacle (most commonly rocks) and has to pass around it, creating a void in the flow directly downstream. They are used in whitewater kayaking to slow down the rate of descent down a river, to regroup after sections, to paddle upstream with ease, and to safely stop to look at what's coming up ahead.

Eddies can be caused by large rocks in the middle of the river, by outcrops on the sides, or indeed by any fixed obstacle in the flow of the river.

 

Recirculating Eddies  - These eddies are commonly to the sides of other features, such as weirs or drops with stoppers. They may also be formed where the main flow runs up against a wall or obstruction and some of the current flows back upstream. In these eddies the flow is constantly moving upstream (or occasionally all over the place), usually being drawn in by a stopper. Although these can be useful for getting upstream quickly (especially for playboaters wanting to get back onto a wave or hole), caution should be taken as the flow is often erratic and novices may be unwittingly pulled into the feature.

 

Falls - Short for waterfalls, these constitute any large drop or fall in height A sudden drop over an edge where water falls free into a pool below. Falls should be attempted by advanced kayakers only.

 

Fastwater- Featureless water moving downstream.  

 

Flatwater - Calm river, lake, or ocean water without rapids or high waves

 

Flow - The movement of water. Used to describe how and where the water travels, eg. "See how it's flowing onto that rock".

 

Haystack - Big standing waves which are breaking on their upstream face. Many rapids will have a series of haystacks downstream of the main hole; riding these is much like bouncing along on a rollercoaster, and can be a lot of fun. Haystacks are a pretty benign form of whitewater, and allow paddlers to show off by "catching air". Big standing waves in a wave "train" following a drop

 

 

Heavy Water - High velocity, turbulent water, usually through rapids and other constricted waterways.

 

Hole - A hole is created when the river current drops over a rock or ledge and circulates instead of continues its downstream flow. A significant feature because it either offers play opportunities or danger of trapping, depending on the power of the hole. The whitest whitewater. This is the area downstream from a drop or rock where there is a boiling action of the water, with a lot of water being re-circulated. This is also known as a "stopper", which is what they do to boats. Some people have named certain nasty holes: Maytag is one memorable one, and that's what it feels like to be in one, upside down. Stay right side up, however, and they're fun to play in/on. Learning to read the water in and around holes in order to figure out what it will do to you if you land in it is an excellent skill to develop; learning how to get out of grabby holes is another good idea. See Hydraulic.

 

Hydraulic (AKA reversals) - This is a hole formed by current dropping over a vertical or near-vertical obstruction (or a drop in the riverbed). If the obstruction is perpendicular to the current flow, uniform, symmetrical, or some combination of all three, the hydraulic can become extremely powerful. The forces generated as the falling flow pulls surface water upstream can be powerful enough to flip a boat and hold it indefinitely. Swimmers caught in such places are said to be "maytagged", for obvious reasons, and it's not pleasant. Most hydraulics will let go of boats, boaters, and other gear after one trip around or so, but other "keeper" hydraulics will recirculate their contents indefinitely. There are some hydraulics, notably those formed by low-head dams, which are known as "terminal hydraulics", again, for obvious reasons, and are to be avoided at all costs. See Hole.

 

Ledge  / Pourover -  Ledges /Pourovers are rocks with flat tops that are just under the surface of the water. Running them can be tricky: if there's not enough water flowing over the rock, the boat may become lodged on the rock. Occasionally, ledges / pourovers also come complete with sharp surfaces capable of putting new holes in boats. Generally to be avoided unless you're sure of what you're doing.

   

 

Low-Head Dam - Envision a horizon line with a riverwide keeper at the base. These dams are often small in size and appear runnable. They are not. You will die. Don’t even think about it, portage these killers.

 

 

Pillow - water that builds up around a rock in the main current.

 

 

Pool - A stretch of calm water on a stream or river.

 

 

Pool and Drop - Many rivers are characterized by fairly short rapids interspersed with flat stretches which make rescue a bit simpler and allow paddlers to compose themselves before the bottom drops out again. Such streams are known as pool and drop rivers, as opposed to continuous.

 

 

Portage - To walk around a feature or section of river, carrying the boat

 

 

Put-in - starting place of a river trip; where you put your boat on the river to begin a run or trip

 

 

Quickwater - The river is fast with a smooth surface at high water levels - choppy at medium and low water levels.

Rapids - A fast, turbulent stretch of whitewater normally accompanied by rocks and a steep gradient.

Reversal - A water feature similar to an eddy where the current reverses back on itself. Reversals are usually caused by rocks or other obstructions on the surface or beneath the water.

Riffles - Light, shallow rapids found in Class I whitewater

Roostertail - spray of water that explodes off a submerged rock or obstacle

Scouting - The act of inspecting an unknown section of a river before attempting it. Always a good way to stay out of trouble

Shuttle - the most dangerous part of the trip. Driving between the put-in and take-out. One-vehicle shuttles require logistical foresight using options such as biking, walking, hitchhiking, etc., to return to the put-in.

Siphon - A bore-hole into or under the main river bed into which the water (and paddlers/boats) is drawn.

Sluice -  Water going through a very narrow passage between two rocks at high speed. Usually terminates in a strainer or something equally nasty, and should be avoided.

Smoker - A stretch of aggressive or violent whitewater.

Standing Wave - A whitewater feature where a wave remains stationary in one place. Used for surfing and other playboating maneuvers. Big waves that often indicate the main channel

Strainer - current clogged with tree branches or debris that allows the water to flow through but could pin you or your boat. Very Dangerous! An obstruction just above or below the surface that allows the water to flow though un-obstructed but will catch and hold a swimmer or floating equipment Strainer: This is what happens when trees, trash, and other assorted items become lodged in rocks in the path of the current. Boats and boaters who float into strainers tend to stay there, so avoid these, period. If you do by some remote chance find yourself swimming into one, try to climb up onto whatever's in there -- you might be able to get over it and float off the other side, or possibly climb out of the water. Many undercut rocks have strainers under them, creating an extreme hazard.

Sweeper – Trees or branches that overhand the river, or sometimes just barricade the river with their branches. Before those overhanging braches knock you out of the boat you’ll have a faceful close up of spiders, hornet nests, assorted rusty fish hooks and something brown and disgusting and you really don’t want to know what that was, do you? Don’t worry about it, you are taking a bath in a second anyway.

Take-Out  - ending point of a paddling trip; where the boats are finally taken from the water

Undercut - an overhanging rock or ledge with water flowing underneath it. A serious hazard! Over time, rivers can erode out the bases of rocks which are in the path of the main current, forming undercut rocks. Undercuts represent an extreme hazard to boaters, since rescue is nearly impossible once someone becomes trapped under such a rock by the force of the current. Some, but NOT all, undercut rocks are characterized by the absence of a pillow on their upstream face: the current goes under the rock rather than bouncing off. Some, but NOT all, undercut rocks may also be recognized by the presence of a current coming out from the under the rock on the downstream side. Avoid undercuts, period.

Vee - These come in two flavors, upstream and downstream. A downstream vee (i.e. the point is downstream) indicates the main flow of the current is passing between two obstructions. Generally speaking, the middle of the vee will have smooth, flat water moving a high speed; this is sometimes called the "tongue". Upstream vees indicate the presence of an obstruction at the point of the vee; they usually also indicate the presence of an eddy just downstream from the obstruction.

Whitewater - Also known as rapids and wildwater. A stretch of turbulent, fast moving water that flows through rocks, over falls, and around other obstructions