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.
Easy – Waves small, passages clear; no serious obstacles, perfect for all ages and abilities. No guide needed.
Medium – Rapids of low difficulty with passages clear. Suitable for everyone, no experience necessary. A guide is preferable for these rapids, but not required.
Moderate – Waves numerous, high, irregular; rocks; eddies; rapids with passages clear though narrow, requiring experience in maneuvering. No previous experience is necessary.
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.
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.
Unrunnable!Just like it says – Don’t even think about it! These constitute waterfalls and other death-traps that should not be attempted.