Unless there is something really spectacular to see ashore, you are better off staying on the ship. Often people feel they must go off and see the port. They ride around in a hot bus or taxi looking at boring scenery, they pay to have a second-rate meal, and the locals pressure them to buy things that will be in next year's garage sale.
Meanwhile, back at the harbor, there is a floating resort with all sorts of facilities and entertainment options available. In the dining room or at the buffet, there is a good lunch, which you have already paid for. As a bonus, it is uncrowded because most of the people have gone ashore because they felt they should go ashore.
In sum, it is perfectly okay to stay onboard in port. You have the ship and all its facilities to yourself. You do not have to struggle with tours or trying to sightsee on your own. There are fewer organized activities but if you just want to relax, it is perfect.