In Belize there is a shore excursion to Goeff's cave which you can book directly through Carnival. They will come to the ship and pick you up and return you when the trip is over. Great little and I mean little island with some great snorkeling around. They will lead the way and point out all the neat stuff...Its a good 20 minute boat ride, but at least you don't have to take the tender all the way into port which is a fairly long tender ride. You can still have time to take a tender into the port if you want to walk around the shops there after your excursion.