International Whitewater Classification

Listed below are definitions of the different river and rapid scales and some safety tips for boaters. Because of rapidly changing weather conditions and other situations, river classifications can change rapidly. Be prepared for these events, check weather forecasts, and don’t overextend your skill levels or equipment capabilities. 

Class I:
Small waves, passages clear, no serious obstacles

Class II: Medium-sized waves, some maneuvering required

Class III: Numerous, high and irregular waves; scouting often required

Class IV: Powerful, irregular waves; boiling eddies; dangerous rocks; congested passages; precise maneuvering required; scouting mandatory

Class V: Difficult, violent waves; big drops; scouting mandatory and difficult; violent current

Class VI: Navigability limited; often considered unrunnable