Your travel agent will give your what type of excursions there are.. Pick before you go .. They are sometimes full when you get on the boat .. If we didn't plan anything we'd get in a taxi and ask them " take us somewhere good " we always end up have a better time.. Cab driver know all the good places.. Have fun
Cruises are a great vacation bargain. There's plenty of entertainment onboard; I got more enjoyment from exploring the port cities / islands the ships visited. Skip Mexico; consider the Caribbean & Bahamas islands.