Board a double-decker motor catamaran and head out to Caracasbaai Bay, where a tugboat that sank 30 years ago has become one of the most unusual snorkel sites in the Caribbean. Coral and tropical fish have made the wreck their home, and a guide accompanies the group through the clear water, pointing out the formations and species that have colonized the hull over the decades. Underwater photos here tend to look unlike anything from a typical reef. After the snorkel, the catamaran deck becomes the setting for a grilled lunch with an open bar, making the return cruise as rewarding a part of the day as the snorkeling itself.