A little more info on the cenotes for those who asked. I don't remember the exact name of the one we went to, but they were just south of Playa del Carmen just past Puerto Adventures. There was no guide at all, we just went in and went where we wanted to without anyone bothering us. The thing that we didn't want, a big tour with a bunch of people around... We looked for smaller cenotes with not much exposure to tourists and that's what we found.