If the increased pressure is high enough, your diaphragm and lungs are going to be in a world of hurt.
Physiological freaks aside, go too deep, and you're dead. Especially when you go from 1 bar to, say, 15 instantly, which is a situation that free divers do not expose themselves to.
Physiological freaks aside, go too deep, and you're dead. Especially when you go from 1 bar to, say, 15 instantly, which is a situation that free divers do not expose themselves to.