Activities The Great Outdoors Advanced Whitewater Kayaking River Feature Terminology Know How to Identify Different Whitewater River Features Share PINTEREST Email Print A Kayak Flips Over on Lower Coliseum on the Cheat River Canyon. Photo © by George E. Sayour The Great Outdoors Paddling Hiking Climbing Skiing Snowboarding Surfing Fishing Sailing Scuba Diving & Snorkeling Learn More By George Sayour George Sayour is an American Canoe Association–certified kayak instructor. He regularly leads workshops on paddling basics, techniques, and safety. our editorial process George Sayour Updated March 18, 2017 A whitewater paddler’s knowledge of whitewater kayaking river features obviously should not stop at the basic whitewater river features terms. Within every features there are varying degrees and nuances that distinguish between even features of the same type. This is a list of those more advanced terms that are used to describe whitewater kayaking river features. Whitewater Ripples or Riffles Class II Boogie Water Eddy Line Whirlpool Horizon Line Rooster tail Tongue Slot Chute Pool-drop Pillow Undercut or Pinning Rock Strainer A strainer in whitewater refers to an obstruction in the water, usually a collection of debris or tree branches, where the river is constricted while flowing through it. Strainers strain the river from things that are floating or submerged in it, including swimmers. Stay away from strainers.