Class III Intermediate, Difficult Longer rapids with strong irregular currents and high irregular waves. Maneuvering required to avoid obstacles and through narrow channels. May require scouting from shore. Class IV Advanced, Very Difficult Steeper, longer with numerous obstacles and constricted passages. Scouting from shore is often necessary.
Rescue is difficult.
Class V Expert, Extremely Difficult Consists of large vertical drops, strong hydraulics, and very swift, irregular currents in heavily obstructed channels. Very violent rapids which must be scouted from shore. Rescue is difficult with significant threat to life in the event of a mishap. Class VI Crazed Team of Experts Class V whitewater carried to the outer limits of navigability. Nearly impossible and very dangerous.