My experiences of Florida have been pretty warm, but I am interested in getting into some of the wrecks on the Great Lakes, I would imagine a dry suit would be required for that. My home is closest to Lake Superior, which is the coldest, and it gets just warm enough in August for those few crazies like me to go swimming.
I am naturally apprehensive around predatory animals too, like crocs and sharks. I try to remind myself that all animals have a natural fear of humans and aren't going to attack unless we piss 'em off or corner them or do something dumb like show up during feeding time with a steak tucked in our BCD.

Forget what you see in Hollywood- they're more afraid of us than we are of them. I don't know how successful I am at that though, since I haven't really had any encounters.