You’ll never feel more alive than when you’re doing the backstroke in an underground cave, basking in the sunlight pouring through a small opening in the rock above. Lurking just beneath the sand ’round these parts are hundreds of mystical cenotes, underground swimming holes rumored by the ancient Mayans to be passages to the afterlife. These divots form when limestone naturally collapses into itself and reveals the swell of groundwater below, and Tulum has a whole bunch of them. The most popular of the bunch is Gran Cenote, where you can rent snorkels—or full-on scuba equipment if that’s your jam—and hang out with the seafood you may be eating later. If you just want to lounge around and do some world-class vibe soaking and munching, check out the breakfast buffet at Cenote Yal-ku.