One of the questions facing the cruise passenger is wherever, and how often, to take shore excursions. Tours that are organized by the cruise lines are often good value and informative, taking you to places that you would not otherwise visit. Choose one that includes places with local color, especially when the native people are making it an occasion.
A cruise line will usually organize half-day and whole-day tours. A particular advantage of these is that you expect the ship to wait for you if you are late back. It is worth bearing in mind that it is your responsibility to return to the ship in time. The captain does not have to wait for you. Your cruise ship will typically have berthed by 8 am and may be ready to leave by 6pm. For this reason I favor the morning for self-organized tours, just in case the taxi breaks down in a remote part of the island.
Visits to sites of historical interest can probably be more cheaply organized by hiring a taxi with friends and negotiating the terms for a morning tour for per $ 10 (US) each. Taxis in the Caribbean are often minibuses, that will hold up to 10 people. You may be lucky and find a good driver who is also a guide but, unless you have studied your guide and know what you want to see, a tour organized in this way may be limited to an itinerary known to the driver, but some are knowledgeable. Expect to be taken to places selling souvenirs by people known to the driver, this can also happens on an official tour when it is more annoying.
The larger the island the more scope for visiting places of interest. Neverheless the smaller islands may offer special themes such as scuba diving or fishing – or simply lying on a sunny sandy beach.