That’s what we did when we went on the Carnival Cruise ship 11 years ago..went to Mazatlan, Cabo, and Puerto Vallarta(Which was the nicest of all three) just stayed in the area around the ship and that was it
Wife and I went to Cancun. Most awesome vacation. But on the last night she was feeling too well. Got home and she still wasn’t well. Went to the doctor and it turned out to be a parasite from something she ate. Was sick for several months.
Don’t trust the food or water.