The snorkeling along around the rocks around SBR is good but you have to go out to the furthest set of rocks for the best chance to see the fish. There is are several areas away from the exposed rocks that are also good but more in open water between the rocks between Flamingo and SBR. There are some rock formations out there you will see several species of coral, sea fans and sponges along with fish out there. I have been snorkeling there for the past 15 years for at least 2 hours a day as long as the water is clear and not churned up. If you go out in the open waters you will see several truck frames along with conch shells that fisherman dropped after they took the meat. The shells are large and plentiful but are beat up and must have been the for a long time. I would also suggest you be careful as boats go by there at times. I have seen almost the tropical fish there and I posted a number of pictures on our November trip.
