Our group did a Helmet Dive. What a great experience. You can wear your glasses and your hair never gets wet. We were down 20 feet and spent about 1/2 hour walking about and feeding the fish. There are divers down with you and a Photographer taking pictures, which you can purchase for $35 on a flash drive. Would highly recommend this excursion.
Third time on this excursion. A really fun time. Great snorkeling and even better Rum Punch (after snorkeling). Good lunch and an even better crew. Don't think you could have a better time anywhere else.