Rivers can seem benign enough -- until their white-water rapids chew you up and spit you out. Which are the most aggressive? See more »

Rafting or kayaking whitewater rapids is an exhilarating way to spend an afternoon. But have you ever wondered who came up with the ratings for the rapids? Who decides how dangerous a rapid is? See more »

Black water rafting is a new take on both spelunking and tubing. What's it like to tube through a cave? See more »

People who enjoy board sports often have a need for speed. But many -- especially those who don't have access to hills or ramps -- don't know how to get it. How can a simple bungee cord help solve this problem? See more »

It's hard enough to swim down and touch the drain in the deep end of the pool. Can you imagine diving 700 feet into the ocean's depths without oxygen? How do these people do it? See more »

You might not think about the physics involved in keeping your canoe afloat as you drift down a river, but this seemingly simple pastime is pretty complex. And is there a difference between canoeing and kayaking? See more »

Cave diving is the most intense, specialized and dangerous form of scuba diving there is. Cave divers explore places never before seen or touched by humans. See more »

Cliff diving is an extreme sport that involves hurling your body from dangerous heights and freefalling at deadly speeds, so how do cliff divers live to dive another day? See more »

Hydrospeeding is a popular extreme sport that involves riding torso-length boards down fearsome river rapids. It's fun, but you should do a little research before you hit the water. See more »

Kayak surfing draws water sport enthusiasts who want to tackle more waves at high speeds. What exactly does this sport entail, and how does it differ from traditional board surfing? See more »