Understanding Whitewater Classifications

Rivers are rated using roman numerals I to VI according to the International Scale of River Difficulty. Note also that a river’s level of challenge changes with fluctuations in water levels; a river rated Class IV at medium water levels might resemble a Class III river at lower water levels, while at higher levels, it might look more like a Class IV+. The rating system used in the Grand Canyon, which rates rapids 1 to 10, pre-dates the modern Class I-VI system of rating rapids. A “10” in the Grand Canyon is comparable to a Class V rapid elsewhere.

***Note that multi-day expeditions can have a wide variety of rapids on a single trip, from class I to class V, so check with your outfitter to get details***

First-time and veteran rafters alike thrive on class II, III and some class IV rivers and rapids. Class V river trips–especially for paddlers–usually require two or more previous trips and previous Class IV experience. When booking your rafting trip with a Rafting America company, make sure you let the outfitter know your comfort and experience level so they can recommend the right trip for you.

Class I

Easy – Waves small, passages clear; no serious obstacles, perfect for all ages and abilities. No guide needed.

Class II

Medium – Rapids of low difficulty with passages clear. Suitable for everyone, no experience necessary. A guide is preferable for these rapids, but not required.

Class III

Moderate – Waves numerous, high, irregular; rocks; eddies; rapids with passages clear though narrow, requiring experience in maneuvering. No previous experience is necessary.

American River Kern River King River

Rogue River

Tieton River Wenatchee River Skagit River

Rio Grande River

Colorado River Green River

Gunnison River Upper Colorado River

Flathead River

Snake River Salmon River

Snake River

Colorado River Green river

Copper River Kennicott River Nizina River

Thompson River Northern Territories

Delaware River

Kennebec River

Deerfield River Miller River

Nantahala River

Chattooga River (section III)

Pigeon River

New River (upper)

Peshtigo River

Note that multi-day expeditions can have a wide variety of rapids on a single trip, from class I to class V, so check with your outfitter to get details

Class IV

Difficult – Long rapids; waves powerful, irregular; dangerous rocks; boiling eddies; powerful and precise maneuvering required. Have an experienced guide. Previous experience is helpful, but not necessary.

Class V

Extremely Difficult – Exceedingly difficult, long and violent rapids, following each other almost without interruption; riverbed extremely obstructed; big drops; violent currents; very steep gradient. Paddlers should have prior Class IV or better whitewater experience with experienced guides who know the river.