A ferry ride from Cozumel brings us here to the gates of Xibalba, the Maya underworld. We're lured by the cenotes of Riviera Maya, a vast subterranean river system hidden underneath the Yucatan jungle.
Historically, sharks left the area when scuba divers entered the water. The bubbles from the regulators scare them off. Since shark dives started in the Bahamas many of the sharks have lost their fear of these bubbles.