Before the rise of 21st century Mexican drug kingpins, and severed heads in the desert, the Mexican Underworld had a significantly different meaning.
Instead of accessing the Underworld through a dirty backdoor in a cantina, pre-colonial Mayan tradition believed the gates to the beyond lay in cenotes.
Just a few kilometers from Valladolid in the Yucatan Peninsula, the landscape is dotted with natural sinkholes, leading straight down into the earth. Unlike their unsightly name, the sinkholes are beautiful and filled with crystal clear, blue-green water. They are easily accessible and have become a tourist hot spot due to their proximity to spring break destinations like Cancun.
Despite their obvious aesthetic attraction, the Cenotes in the region have a fascinating history, dating back to the Mayans who inhabited the Yucatan before colonialism. Since the Mayans believed the holes led to the afterlife, they would often drop important objects into the cenotes. Some legends also state they were used in human sacrifice, an oft-debated part of Mayan history.
Since most cenotes in the region were explored and studied by archeologists in the early 20th century, you are unlikely to be swimming with the remains of a Mayan sacrifice. You are more likely to simply enjoy a relaxing dip among the stalactites and radiant beams of sunlight from the outside world.
via Atlas Obscura http://www.atlasobscura.com/places/cenote-xkeken