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Understanding River Rapid Classifications

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Whitewater Rafting

Understanding River Rapid Classifications By Richard Chapo.


There is something about rapids on a river that make people excited. Oh, yeah. I gotta try that! Before you hop into the river on a kayak, raft, canoe or branch, you need to take a minute to understand river classifications.

Not all whitewater on a river is equal. Some rapids come in the form of minor disturbances that are fun, but not too treacherous. On the other end of the scale, there are the rapids where you are sure death is feet away and it may very well be. So, how do you know if you are going to get a little excitement, a medium level or a meeting with your maker? You just look up the classification of the rapids in front of you or read on.

Rivers are classified in the same way across the world. Hey, at least we can all agree on something! In the case of rivers, the classification is known as the International Scale of River Difficulty or ISRD. There are six basic classifications, but people have also developed sub-classes. We’ll avoid those for now and look at the big six.

1. Class I – This is basically your easiest rapids. We are talking minor speed bumps on the river. You are only going to get hurt if you are drunk or can’t swim and fall out of the boat. These rivers are so tame, you might not realize you are even on rapids.

2. Class II – A bit more adventurous, but not much. These rivers tend to have daring looking whitewater, but not in the actual path you will be taking. You can more or less just float and bypass everything. Good for beginners, but probably will not get the adrenaline rushing.

3. Class III – Now we are starting to have fun. Class III rapids are considered excellent for moderately experienced boaters. You are going to get thrown around a bit. You are going to get water in your boat. You should have an understanding of how to maneuver in rapids to avoid rocks and such. In kayaks, you can flip if you are not careful. Canoes can be filled with water. Definitely the first stage where your adrenaline gets going.

4. Class IV – Now we are weeding out the people not that interested in whitewater experiences. This is the level you see on television shoes. Water is thrashing everywhere and you need to know what you are doing. You should walk the shore and scout the rapids to pick out a course before entering them. If you are kayaking, you MUST be proficient at rolling because there is a very good chance you are going to flip in or next to a hole.

5. Class V – This is a serious river. The rapids may not actually be that much worse than a Class IV river, but they typically exist over longer distances. Shooting wild rapids for 200 feet is one thing. Shooting them for a mile is an entirely different situation. You should be an expert. You should scout the river carefully and closely. You should sign your will before going down.

6. Class VI – Insane. Yep, you have to be insane to go down these. Death is assured. These are rapids that make any normal person shake their head. The brutal truth is nobody should go down these. Examples include fast water shooting down multiple waterfalls in a canyon with 40 foot walls and water that is no more than 10 feet wide. If you get in trouble, nobody can help you. You die. Only a person with years of experience and a death wish should try these babies.


For most people, the Class II through IV rivers do the trick nicely. Once you become very proficient with them, Class V will usually be good enough for the rest of your career. Class VI can be done, but you are tempting fate even though you are an expert in your kayak.


Rick Chapo is with - makers of journals for white water rafting trips