About 1km south of amusement park Xel-Há is the turnoff to the enormous Dos Ojos cave system. Operating as a sustainable tourism project by the local Maya community, Dos Ojos offers guided snorkeling tours of some amazing underwater caverns, where you float past illuminated stalactites and stalagmites in an eerie wonderland. For diving, you must go with a dive shop.
With an extent of about 83km and some 30 cenotes, it’s one of the largest underwater cave systems in the world. One of the most popular sites for experienced divers is the Pit, a 110m-deep cenote in which you can see ancient human and animal remains. If you are not a certified diver, you can pay the price of admission and go swimming or snorkeling. A dive shop at the park's entrance runs cavern and cave dives, the latter requiring cave diver certification.