Well were going up not this weekend but next to GA, to dive Gray’s Reef Marine Santuary, it is just off Sabel Island.. about 40 min. from Jax, 20 min. by boat. Killer dive site.. viz is 15-80ft. from May through Aug and the water at bottom 80 ft. is about 79 degrees this time of year.. it gets warmer in June.. so a shorty is probably all you need. Here is a killer dive map of all the recks off the GA coast and if your in Jax.. that is where you will want to dive anyway...
http://www.southgeorgiadivecharters.com/default.asp?iId=IHJEF
Good luck! Watch for the hotels.. and the city of Jax is mostly crappy. WE lived there for like 2 years.. south side and beaches and near GA are the only decent spots.. but.. good news is your only a 2 hour drive from O-Town and Mickey Mouse!
Ponce Inlet if you like sharks is only about an hour from you.
Caio.
Take care! Have fun!