Thank you so much @thekittygirl, and I need to apologize for the late reply! I somehow missed a handful of comments here!
That's so cool that you just saw a show on cenotes and then I post about them! I've heard that they're all connected too ... it is really fascinating. There are some you can go into, cave-like, but underwater and apparently the snorkeling is amazing! Not sure if I'm up to that one haha