Check your arrival/departure times against the ferries schedules. We have friends who live a few minutes outside of Playa. On our last Western, they wanted us to come see their new house. After checking arrival/departure time we realized it was a pretty short day (all aboard around 4, I think) and we would barely have time to make it there and back (I wouldn't want to trust that the last possible ferry would (1) run, (2) be on time, (3) give me time to walk back to the ship. So, they came over to Cozumel instead for lunch. Still hope to see their house someday.