Idaho Rivers

What do the river classifications mean? 

International Whitewater Classification

• 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