A place in a river similar to a whirlpool where the water flows upstream. This effect is caused by a turn or projection on the bank of the river or a rock midstream. The eddy is created behind the rock, bend or projection.

Eddies frequently occur beside surf waves, vees, and waterfalls. In fact, rivers are generally littered with them except when in flood. Eddies are good places to rest while deciding what to do next. Sometimes, the eddy is where you have to line up to play in the whitewater.