There are a large number of sports that are related to water.
The following is a List of water sports, divided by category. These categories are based on the relation of the sports to the water, and there are many more sports to be added. Some of the sports include only one part related to swimming, as for example Triathlon. This system has the disadvantage that that some sports may fit in more than one category. Here they are only listed in one.
Apnea is the practice of not breathing for extended times.
Underwater rugby is rugby played under water with a ball that has been rendered neutrally buoyant. Surfacing to breathe is only allowed without the ball.
Underwater hockey is hockey played under water with short wooden Y-shaped sticks and a heavy puck. Surfacing to breathe is only allowed when you are not pushing the puck.