Whitewater is formed in a rapid, when a river's gradient drops enough to disturb its laminar flow and create turbulence, i.e. form a bubbly, or aerated and unstable current; the frothy water appears white. The term is also used loosely to refer to less-turbulent but still agitated flows.

A solo kayak paddler performs a high brace in foamy water. One of the hazards of whitewater paddling is that highly-aerated water decreases the effect of buoyancy.

There are many different types of whitewater craft that people use to make their way down a rapid, preferably with finesse and control. Here is a short list of them.

Whitewater kayaks differ from sea kayaks and recreational kayaks in that they are specialized to deal with moving water better. They are often shorter and more maneuverable than sea kayaks and are specially designed to deal with water flowing up onto their decks. Most whitewater kayaks are made of plastics these days, although some paddlers (especially racers and "squirt boaters") use kayaks made of fiberglass composites. Whitewater kayaks are fairly stable in turbulent water, once the paddler is skillful with them; if flipped upside-down, the skilled paddler can easily roll them back upright. This essential skill of whitewater kayaking is called the "Eskimo Roll," or simply "Roll." Kayaks are paddled in a low sitting position (legs extended forward), with a two-bladed paddle. See Whitewater kayaking.

Rafts are also often used as a whitewater craft; more stable than typical kayaks, they are less maneuverable. Rafts can carry large loads, so they are often used for expeditions. Typical whitewater rafts are inflatable craft, made from high strength fabric coated with PVC, Urethane, Neoprene. While most rafts are large multi-passenger craft, the smallest rafts are single-person whitewater craft.

Catarafts are constructed from the same materials as rafts. They can either be paddled or rowed with oars. A specialized cataraft, designed without any metal frame, is a Shredder. It was invented in 1982 by Tom Love is manufactured by his company Airtight Inflatables in Ohio Pyle, Pa. A Shredder is specifically designed to be paddled. It is usually paddled by a two person crew, though highly skilled paddlers are able to negotiate extreme whitewater in a Shredder paddled as a solo boat. Typical catarafts are constructed from two inflatable pontoons on either side of the craft which are bridged by a frame. Oar propelled catarafts have the occupants sitting on seats mounted on the frame. Virtually all oar powered catarafts are operated by a boatman with passengers having no direct responsibilities. Catarafts can be of all sizes. Many are smaller and more maneuverable than a typical raft.

Canoes are often made of fiberglass, Kevlar, plastic or a combination of the three for strength and durability. They may have a spray cover, resembling a kayak, or "open," resembling the typical canoe. This type of canoe is usually referred to simply as an "open boat." Whitewater canoes are paddled in a low kneeling position, with a one-bladed paddle. Open whitewater canoes have large airbags to prevent the boat from being swamped by big waves and holes. Like kayaks, whitewater canoes can be righted after capsizing with an Eskimo Roll, but requires more skill.