Hey, you are in luck. Ga just happens to border SC (last time i looked). The Savannah River basin runs the SC/GA border starting at the NC state line. Lakes in the chain are Jocassee, Keowee, Hartwell, Strom Thurmond (formerly Clarks Hill)
The first three in the chain are popular diving sites for Divers from several states with Jocassee being the prime site. We have an area for walk-in dives that instructors and shops from several states use. We also have a couple of boat operators in the area ( myself being one) for guided dives or for trips to the "Wall" and "Chinese Junk". directions to the lake are simple.
Take I-85 North out of Atlanta and take the frist exit in SC, Hwy 11.
40 mile or so and look for the signs to Jocassee and Devils Fork State Park. On the road to the park you will see a sign for
"Off The Wall Charters". He can answer any questions you may have as well as offer air fills and trips. You can also email me if you have any other questions. I believe you can also email SAMSLIQUIDBLUE on this board and she can give you info as well.
Now back to your original question. I am told that some Atlanta shops will sometimes use Lake Lanier. Check with your local dive shops for other info.
Foothillsdiver