Rafting is divided into six groups (“class”) by weight. these are:
Class 1: Very small rough areas, might require slight maneuvering. (Skill level: very basic)
Class 2: Some rough water, maybe some rocks, might require some maneuvering. (Skill level: basic paddling skill)
Class 3: Whitewater, small waves, maybe a small drop, but no considerable danger. May require significant maneuvering.
Class 4: Whitewater, medium waves, maybe rocks, maybe a considerable drop, sharp maneuvers may be needed.
Class 5: Whitewater, large waves, large volume, possibility of large rocks and hazards, possibility of a large drop, requires precise maneuvering.
Class 6: Class 6 rapids are considered to be so dangerous that they are effectively unnavigable on a reliably safe basis. Rafters can expect to encounter substantial whitewater, huge waves, huge rocks and hazards, and/or substantial drops that will impart severe impacts beyond the structural capacities and impact ratings of almost all rafting equipment. Traversing a Class 6 rapid has a dramatically increased likelihood of ending in serious injury or death compared to lesser classes.