Some accounts of the CSS Georgia's demise said that they heard an explosion. But, it is clear that Confederate sailors opened the ship's stop-cocks, flooding it.
Four years later, dynamite was used to destroy the Georgia and other obstructions in the Savannah River. After that, the ship all but disappeared to history until rediscovered 100 years later during dredging. In 1986, divers pulled up two of the Georgia's 6 cannons, one still stuffed with live shells put in backwards to spike it. Last month, the other four were retrieved from the river bottom. At least one of the 1986 cannons is on display at Old Fort Jackson as I saw it back in April.
The Georgia's propeller is deep in the river much. It and other large pieces were mapped out months ago by archaeological divers.
This article also contained a lot of information on the diving being done at the ship.