While most rocks in the whitewater environment are fine to interact with there are some you should be aware of.
All rivers have rocks and you are going to hit one sooner or later. If you see a rock, look away from it and paddle away from it. Avoidance is definitely the best cure in this situation. If you do hit a rock, lean and edge toward it. Lifting your edge and tilting your boat towards the rock will allow the water to flow under your boat and prevent it from flipping you over. From here you can push yourself free and clear of the rock or stay in a safe position whilst your friends set up a rescue for you. See the White Water rescue section.
Remember that the bottom of the river is full of rocks and it’s easy to snag your foot on these rocks, so never stand up on the river bed or on rocks under the water in moving water. If you do take a swim in moving water use the safe swimming technique to get to the safety of the shore before standing up.
If you see a rock that the water is running up against and there is no pillow (water deflecting off it) stay away, it is probably undercut. An undercut rock occurs when a softer layer of rock under the water erodes away and forms a cave or gap. Often these under water spaces get chocked up with branches and other debris that can snag a swimmer. An undercut can be seen below the rivers flow, above it or both as it may have been created at a different water level to the flow you are on. It is often difficult to escape from an undercut and they are always best avoided.
If you see or are told about a sieve on a rapid or a river make sure you avoid them as they can be fatal. Sieves are gaps in a rock or collection of boulders that water flows through. Imagine a toilet bowl flushing, this is what they are like. They will drag anything and anyone into them if you get close and often narrow as they go. In many situations they are jammed up with other rocks, trees and debris and in most situations if you go in to one you will not come out. Often sieves can not be seen or easily recognised. Make sure you know about the hazards on any rivers and rapids you are going to run.
Always wear a good helmet as this is the best protection from rocks.
If you are unsure of wether a rock or rapid is safe or not, avoid it. Take a different route or portage round the section involved.