Rapids

Why is the section of the Colorado River running through the Grand Canyons the only river rated 1-10?

Public Comments

1. I would guess it has something to do with the total number of people and the number who have little to no rafting experience but want to run the Grand anyway. It is just a broader scale that allows more distinction (exactly twice as much distinction as a 1-5 scale). Also... there is no part of the Grand that is considered "unrunnable" so the Class VI category is not necessary. So... guide companies started using a more descriptive scale to differentiate between a 6 rapid and an 8 rapid (both of which might be Class IV) under the standard system. It's just a way to let people know... "this is going to be more gnarly than the last rapid... so you might wanna hang on."