I have done this excursion. You meet the boat at the pier in Hamilton behind the Bank of Bermuda, just past the ferry dock. Walk from the ship about 3 minutes.
For this excursion they usually use their larger ship, about 50ft cabin cruiser.
You should make reservations in advance (web site or phone or walk accross the street from the pier in Hamilton, office is down one of the little lanes between the stores.).
First you get a nice little tour as you sail through the harbor. First stop is a very small island. New snorkellers get to try out equipment and get some instruction. Experienced snorkellers can circle the island . I did say it was a small island. After about 20 minutes or so it's back on board and out to the wrecks. Two wrecks are side by side underwater. (Inspiration for Peter Benchley's book "The Deep"). At least one and probably two crew will get in the water with you to point out the "highlights" of what you are seeing under water. One wreck was a wooden paddle wheeler and you can see the paddle wheels and boiler as well as part of the cargo ,cement in bags . There is a neat story that goes with both wrecks , I'll leave that to the crew to tell you. Third stop is a coral reef in shallow water (although you are a few miles out to sea). Great color and fish here. They will then take you back through the harbor by a slightly different route. You get a running tour and lots of information. Whole thing is about 4 hours and is the best overall snorkel tour I have ever taken .
They provide all eqipment including masks with corrective lenses.
Do order the hot dog on the way back in, you'll be hungry and it will taste good.
Tell the OcConners ' (the folks that run the tour) that Bill from NY says hello.
Get them to tell you about the guy who waited 4 years to go out with them, ME.