Snowmobilers should travel in groups of 2 or more, and stick to designated trails. Do not operate a snowmobile if you have been drinking alcohol. They do not steer if you are slowing down. You cannot avoid an obstacle by cutting the throttle you need to maintain your speed and steer away from it. Most injuries result from running into docks, other watercraft, or tree stumps.
Most injuries occur to riders with little experience operating a jet ski.
Jet skis are much more likely to cause injury or death than boats. All riders should wear US Coast Guard approved life jackets. All riders should have attended a safe boater course that includes instruction on using jet skis. Do not use a jet ski if you have been drinking alcohol. Take a training course before riding ATVs.