It’s been some years since I dove out of OC, MD, but when I did there was only one game in town. This is probably the same one you refer to here. I also discovered there was no boat out of anywhere in Delaware at the time, so I had to come down to OC from Rehoboth Beach to get on a (the) dive boat.
In the limited research I’ve done recently, it seems to me that working down the East coast there are large gaps in dive boat coverage. There are a number in Long Island, quite a few in NJ, none in DE, this one in MD, none in VA, several in NC, none in SC or GA, and then a lot down the East coast of FL.