One of the strangest phenomenon's ever seen can found about 30 minutes off the coast of Cancun - the Cave of the Sleeping Sharks. Science says that these creatures need constant motion in order to breathe, but 70 feet below the surface inside this cave they're perfectly still. The phenomenon is caused by fresh water bubbles that are emerging from underwater springs. These bubbles oxygenate sharks, which in turn allows them to breath while remaining still.
