Freediving
Most people don't really know about freediving when compared to its more popular counterpart, scuba diving. Suba divers use oxygen tanks and other gear to assist them with breathing underwater, freedivers do not use any respiratory gear. If you're to get hurt, stuck, or turned around in any way while freediving, you very well might drown.
It's Part of the Job
Freediving is extremely dangerous, but to some, freediving is much more fun than scuba diving because you feel like you're actually part of the environment. There have been 417 recorded freediving accidents, and 308 of them have resulted in death. That's a pretty wide margin.