This is probably the most important thing to have on the river. This will help you to stay out of trouble. By having a clear head and being relaxed you will be most able to enjoy your whitewater experience. All of which the club has and will supply. The group will need a waterproof first aid kit and throw ropes for anyone capable of using one.
Whistles are very useful for keeping the group in touch over the noise of the river.
Clothing Your going to need very little on the river. You should bring a swimsuit and towel, and if it's cold enough a synthetic insulating layer for your top. We use the so called Farmer John style wetsuits to give your shoulders freedom of movement. Your going to want to have something covering your arms and chest in cold weather. Wool sweaters over the top work well.