The only basic training that I'm aware of in SC is the Marine Boot Camp at Parris Island. If that's the case, then diving in NC is not an option IMHO. I think the closest dive operation in NC from there is in Wilmington (which is 5 hours away). If it is Parris Island and you're flying into Charlotte and then planning to dive out of Wilmington, you're looking at a 3.5 to 4 hour drive from Charlotte to Wilmington and then a 5 hour drive from Wilmington to Parris Island.
If it is Parris Island, then your closest dive operation is going to be in Charleston. There are several good dive operations out of Charleston (Charleston Scuba is one) and there are numerous offshore dive sites. However, some of the dives do require AOW certification. If you really want a unique experience and blackwater diving doesn't bother you, you might enjoy diving the Cooper River for Megalodon teeth (and other fossils). That being said, the best guy to use for a Cooper River dive is Captain Tom McMillan. However, Cooper River charters is not a full time job for him. So, he only does charters on weekends (to my knowledge). We'll be diving the Cooper with him in September.
If you really are close enough to get to Wilmington, NC in a reasonable amount of time, there are also several good operations there. Someone already mentioned Aquatic Safaris. We're diving with those guys the end of August on the Rosin, Markham, and Hyde. The Markham and Hyde are two of the more popular dive sites on the coast of NC. Again, some of the Aquatic Safari dives will require you to have AOW certification.
The Nitrox cert will also be a must on SOME of the dives out of either Wilmington or Charleston.
Hope this helps.