At Squamish Watersports, we use the following internationally recognised classification system:
Moving water with a few riffles* and small waves. Few or no obstructions.
(Riffle: ''a rocky or shallow part of a stream or river with rough water.'')
Easy rapids with smaller waves, clear channels that are obvious without scouting. Some maneuvering might be required.
Rapids with high, irregular waves. Narrow passages that often require precise maneuvering.
Long, difficult rapids with constricted passages that often require complex maneuvering in turbulent water. The course may be hard to determine and scouting is often necessary.
Extremely difficult, long, and very violent rapids with highly congested routes, which should be scouted from shore. Rescue conditions are difficult, and there is a significant hazard to life in the event of a mishap. The upper limit of what is possible in a commercial raft.
The difficulties of Class V carried to the extreme. Nearly impossible and very dangerous. For teams of experts only. Involves risk of life. Class VI rapids are not commercially raftable.
Why can a river’s classification change?
1) water level
The numeric figure associated may vary with changing water levels. Usually, high water levels increase the difficulty of rapids. However, this is not always the case. Some rapids become more technical and more difficult at lower water levels.
2) the water craft
The classification system does not take into account the type of boat being used. Some rapids may present particular challenges for rafts, while other rapids may be more difficult for a whitewater paddler in a kayak.
3) Natural disaster
Finally, major events like landslides, ice storms or floods can change the shape of rapids, thus altering their classification.
Assigning numbers to rivers is subjective. Rivers can change at anytime, but thankfully this doesn't happen too often.
If you have any questions, please don't hesitate to ask: