I would like to reccomend the Mayan Reality Tour. Get on Yahy's bus too, she is absolutely adorable.
We saw flamingo's, a Mayan ruin and a newer (lol) church still in use today, probably built in the 1800's, then we were off to a cemetary where we learned to identify Mayan plots vs Spanish ones. From there we stopped at a 16th century cathedral, absolutely beautiful and then stopped for a lovely lunch at a tiny cantina run by a couple of very gracious ladies. We had to import a few chairs to accomodate everyone.
Then....the highlight of this tour, a visit to a Mayan family home. Such sweet loving people. The most humble of dwellings and standard of living, but the sense of family and devotion to one another was a humbling experience. Made me think about the true meaning of wealth.
BTW, you CAN give money to this gentle family. We asked first of course and Yahy told us that it was ok to do so. They raise turkeys, chickens and vegetables, but they can always use some other staples that money can buy.
At each of these destination points, we got off of the tour bus, took pictures, wandered around, climbed the ruins, and had an awesome, awesome time.
If anyone happens to choose this excursion, I hope you will have as wonderful a time as we did.
A sidebar to this tour...one of my daughters professors had allowed her to take time away from class to go on this cruise, providing, she do an obligatory paper and presentation based on her tour of a Mayan ruin. Not only was she able to gather all of her facts and pics etc. from this adventure, but, Carnival's media director Chris, happened to go on this same tour for filming purposes, so my dd was able to include the excursion video in her presentation, with tons of shots of her actually taking the tour. So very perfect.