Probably a niche market on the mainland.
If it was profitable someone would have done it a long time ago.
I guess you could pick any of the Fort Lauderdale resorts and take a very short trip to
many dive operations.
For northeast diving you could stay in Camden New Jersey and take a 40 mile ride to Atlantic City
to dive the warm, clear, calm waters of the North Atlantic. We define warm clear and calm as, 65%, 6 feet visibility and less than a 12 mile an hour rip tide.