From the Mayan dzonot, meaning "well."
A cenote is a deep water-filled sinkhole in limestone that is created when the roof of an underground cavern collapses. This creates a natural pool which is then filled by rain and underground rivers.
Some cenotes are vertical, water-filled shafts, while others are caves that contain pools and underwater passageways in their interior. Cenotes are prevalent in the Yucatan Peninsula, where there are over 2000, and they are the area's main source of water.
Cenotes were ritually significant to the ancient Maya because they were considered passages to the underworld. The Sacred Cenote at Chichen Itza was used for sacrificial purposes: human and animal skeletons, as well as sacrificial objects of gold, jade, pottery, and incense have been dredged from the cenote.
Cenote diving is a popular activity in the Riviera Maya. The water in cenotes tends to be very clear as it is rain water which has filtered through the ground and has few suspended particles. Here are some cenotes which are excellent for swimming, snorkeling or diving:Alltournative Jungle Maya Expedition