Best trip ever. Caught three different types of "big game" fish. And the water was incredibly clear. I could see the fish when they were fifty feet down.
But on a cruise ship I think your off ship trips are very short.
My advice is to plan your time you'll have on the ship. Depending on the line and size of the ship, you'll likely have a lot of activities to choose from. Bottom line is enjoy the actual cruise. You need to find out how much time you'll actually have on land and then maybe talk to your cruise director for advice. You might Google your land stops for suggestions, too.