The Yucatan Peninsula is rife with deep, sometimes creepy and hauntingly beautiful underwater caves called cenotes. Some have multiple layers of fresh water, seawater, stalagmites and stalactites and even trees. Many remain undiscovered and their depths unexplored. Freediver and scuba instructor Julien Borde, of Playa Del Carmen, explores this subterranean world for a living. Dive deep, hold your breath and don't forget to open your eyes.