If you've ever tried hiking, mountain biking or camping, you may have found you caught the outdoor adventuring bug. These activities frequently inspire people to become outdoor enthusiasts who look for the next adventure sport to try. Adventure sports challenge the body and offer an exhilarating escape from the day to day. They include activities such as rock climbing and bouldering, skiing, kayaking and canyoneering, to name just a few.
In 2004, nearly 160 million Americans participated in some form of active outdoor recreation. That's everything from fishing to snowboarding to the more extreme sport of mountaineering [source: Outdoor Industry Foundation Participation Study]. But whether you're a weekend warrior, expert athlete or just testing the waters of adventure sports, there's one activity waiting for you no matter what your skill level: white-water rafting.
In white-water rafting, participants guide and paddle a raft through whitewater, or a river's rapids. The sport's popularity began to grow when it became part of the Olympic Games in the 1970s. Today it's estimated that between nine and 10 million people have tried white-water rafting, with about three million rafters running a river more than twice a year [source: Wilderness Medical Society].
So how are rapids classified? What are the different types of white-water rafts? Find out in the next section.