If you fall overboard and you're not wearing a personal flotation device (PFD), you're probably going to die. In water colder than 60 degrees, shock and swimming failure make your chances of survival even slimmer. A PFD will keep you afloat after you're no longer able to move your arms and legs. But if you go overboard at night, in fog, in choppy seas, or when someone didn't see you go over, your chances are still slim. You might be out there floating around alive, but you might never be spotted and therefore never be rescued.