Bohio is closed. BWD is not under contract with Carnival. BWD and GTDC both use 26' Carolina Skiffs. If you're going to snorkel off the beach please use a flag or wear a bright color shirt. It's a fair swim out in a lot of places.
You currently have 2 choices for diving on Grand Turk
Blue Water Divers info@grandturkscuba.com
Grand Turk Diving info@gtdiving.com
Full disclosure I am connected to the latter.