In the Caribbean, unless it is something REALLY, really specific, or a trip to a different island, it's basically always cheaper and way better to do a trip yourself, versus cruise ship tours. Think about it, the cruise ship tours, the ship gets a cut and then the provider also gets paid. Cut out the cruise ship markup and you get a much more personalized tour, for cheaper, and better. Other places around the world, where there are security issues, perhaps do cruise ship tours, but not in the Caribbean.