The entire Yucatan Peninsula (the region of Mexico where Cancun is located) is made of pourous limestone. Below the surface freshwater underground rivers flow. When the limestone collapses the water is exposed partially or totally and a beautiful cenotes is born. They can be completely open (like a lake) or just have a small opening (like a cave). Cenotes were very important to the ancient Mayans, who considered them to be portals to the underworld. At Xenotes Oasis Maya, you'll explore four cenotes while kayaking, zip lining, snorkeling, rappelling or just relaxing and drifting in an inner tube.