Class II:
Novice
Straightforward rapids with wide, clear channels. Rapids that are at the upper end of this difficulty range are designated "Class II+".

Class III:
Intermediate
Rapids with moderate, irregular waves. Rapids that are at the lower or upper end of this difficulty range are designated "Class III-"
or "Class III+" respectively.

Class IV:
Advanced
Intense, powerful but predictable rapids requiring precise boat handling in turbulent water. Rapids that are at the upper end of this difficulty range are designated "Class IV-" or "Class IV+" respectively.

Class V:
Expert
Extremely long, obstructed, or very violent rapids which expose a paddler to added risk.

Class VI:
Extreme and Exploratory