Underwater Hockey

Given the hard hits and frequent fights so common in ice hockey, it's difficult to believe that anyone could imagine a more potentially hazardous version of the sport. But with the added element of a potential drowning, underwater hockey makes frozen-water hockey look like child's play.

The rules of liquid-water hockey are similar to that of it solid-state counterpart. The difference: Players use wooden or plastic sticks about the size of a banana to push around a metal puck around the floor of a pool.

The action is especially exciting for spectators, who can only really see ripples on the surface from the action below.