Need Excursion Recommendations: 7 Night Princess Cruise Southern Caribbean

We are doing the same in December, on the Crown Princess, but different ports (we hit St. Thomas, St Maarten, Antigua, St Lucia and Barbados) . Here's what we're doing in the couple of ports we have in common:

St Thomas: We've been there a lot, so we're taking the ferry to Water Island and renting a golf cart from Rachel's Rentals to explore the island on our own.

Barbados: We booked one of the snorkel tours through Savvy on the Bay Beach Club on Carlisle Bay, which includes RT transportation from the cruise port, a snorkel trip, and use of the club.