Some of the best diving around the Largo area is just southeast of Molasses Reef. Lot of nice patch reefs between CarysFort light and Pennycamp. There is a nice reef called Triumph Reef with massive elks and stags, tame Manta Rays the size of Volkswagens. Top of the reef breaks water at low tide and drops off to about sixty feet before colors wash out. But don't take anything out of the park. The park rangers and Marine Patrol are everywhere around Bill Baggs Park and Cape Florida, and of course Pennycamp.
Nice wreck out there too, The USS Bentwood. Last time I saw her she was sitting on the edge of the shelf, bow is in about 90 feet of water sterns about 140. Two tank dive, but very nice growth for so deep. The wreck was at one time in shallow water when she got most of her growth, but has slowly been working her way into deep water. I haven't dived there in 10 years; she may be over the shelf by now.