Much of our trip was dedicated to exploring caves, cenotes, and Mayan ruins. Cenotes are water-filled limestone caves that some people even scuba dive in. We didn't dive, just enjoyed swimming. Except for a few sites, the Mayan ruins were deserted and climbing them was allowed! The tourist hordes stayed in Cancun and the nearby sites only. The highlight for us was Calakmul, across the border from the more famous Tikal, it was massive and due to the remoteness of the site, was also filled with wildlife.
Our guide told us that the Mayan leaders would climb to the top of the largest pyramid and cut their genitals to show their strength, which seemed to us more like a demonstration of insecurity.
We enjoyed Merida, where cartels send their families to live because it is one of the safest places in Mexico. We found a crowd of people dancing to music in the street and joined in with salsa ourselves.
In Rio Lagartos, we hired a boat to take us around to see flamingos, as well as a caiman that knew that if he came over the boat pilot would throw him a snack. And we visited a beach with supple mud and took a mud bath.