International Scale of River Difficulty

The following classifications are according to American Whitewater. If rapids on a river generally fit into one of the following classifications, but the water temperature is below 50°F or if the trip is an extended one into a wilderness area, the river should be considered one class more difficult than normal.

Class I

Moving water with a few riffles and small waves. Few or no obstructions.

Class II

Easy rapids with waves up to 3 feet and wide, clear channels that are obvious without scouting. Some maneuvering is required.

Class III

Rapids with high, irregular waves often capable of swamping an open canoe. Narrow passages that often require complex maneuvering. May require scouting from shore.

Class IV

Long difficult rapids with constricted passages that often require precise maneuvering in very turbulent waters. Scouting from shore is necessary, and conditions make rescue difficult. Generally not possible for open canoes. Boaters in covered canoes and kayaks should have the ability to Eskimo roll.

Class V

Extremely difficult, long, and very violent rapids with highly congested routes, which should always be scouted from shore. Rescue conditions are difficult, and there is significant hazard to life in the event of mishap. Ability to Eskimo roll is essential for boaters in kayaks and decked canoes.

Class VI

Difficulties of Class V carried to the extreme navigability. Nearly impossible and very dangerous. For teams of experts only, after close study has been made and all precautions have been taken.

For more information on river classifications and safety see the American Whitewater web site.