Lake Murray is good for diving? No kidding? We used to go up there a lot for family reunions when I was a kid. I guess it's too cold for diving up there this time of year...for most people, but I used to diving in the Pacific. Usually 53 degrees is about as cold as it gets around the Southern California Islands but I've been in water as cold as 48. Anyway, I have a drysuit so that makes a big difference.
Where else in OK, do you go?