Just my personal addition to this note, a friend of mine adopted a kid from the DR. He tries to go back there with her every year or two, so she gets to know where she was born. Anyway, he did one of these dives. He'd been to Akumal, and dove the Cenotes before. He didn't know what he was getting into. Said the climb down into the cavern was pretty sketchy. He also wasn't aware of how far in they were going to go, and once they got a little bit in, he said he didn't really think he could find his way back out, and said he would have turned around if he knew for sure he'd find his way out on his own. All in all, he wasn't very happy, but also wasn't at all aware what he was getting into.

Tom