Natural World - Season 23 Episode 12

Beneath the jungle-clad temples of Mexico's Yucatan, a startling discovery has been made: the largest network of flooded caves and underground rivers in the world. The intrepid cave divers exploring this surreal landscape have made remarkable discoveries: bizarre new animals, as well as the skeletons of the ancient Maya and the offerings they made to the spirits. This was their underworld, and its secrets are finally being revealed.