I have been there twice. both time we went to a little mexican village on the beach called Mahalajua. first time the tourist trade had not hit it too bad. the last time it was a bit more touristy, but still very rustic mexico.
I am not sure there is a whole lot more to do other then to visit the shopping area there at costa maya.
WE took tour of Chacchoben Mayan Ruins thru Carnival. It was very interesting. Hot and a lot of walking though. Aftwards we ate lunch in one of the restaurants right off the pier in the shopping area. Very reasonable and delish.
No beaches? Ok, we did a great snorkel excursion through the ship. Mamasita's is at the terminal with a nice swim up bar. Mahual is the town about a mile away from the pier. It's mainly a fishing village. You can rent golf carts there, too. Not sure how much it was because we spent our day on a great snorkel trip.
I just got back from there,,,do book some type of tour as the port is literally in the "boonies"...not much to see ex.shop and eat...I also went to ships tour of ruins,,,about 3 hr.total...Interesting to see and hear about Mayan culture....then can wander around port area after...