IMO you need to be suicidal not to know how to swim, there is just to many ways to be stuck in water and knowing how to swim will make the differance between life and death. I have a friend that was walking beside a pool at a party one night and fell in, started flailing around like a lunatic splashing water everywhere then stopped moving after 30 seconds, we all thought he was screwing with us and playing dead, when in reality he did not know how to swim and had started to inhale water. I jumped in and dragged him out and he coughed up a bunch of water, if i had not im unsure if anyone else would have saved him intime i was the only sober person there at the time.