How are rapids rated?
Rapids are rated on a scale of 1–6. Class 1: fast moving water, Class 2: Splashy waves, Class 3: waves or holes big enough to swamp an open canoe, Class 4: numerous big waves or holes with obstacles to avoid, Class 5: Large chance of raft flipping, Class 6: un-navigable in any raft, not available commercially (Niagara Falls)!