Alcatraz: Inescapable?

Alcatraz is a prison on a island that doubles as a mental asylem. The very fact that a prisoner sent there will be sharing space with the clinically insane just seems like a terrible thing to do to someone. Alcatraz was in the middle of one of the coldest lakes in the US, so, that is how it was literally inescapable. But, share part of your life with someone that is insane, and you might not be able to forget for a long time. and those are the only two reasons I can think of.