The cenotes of Yucatan

If you look at a map of Mexico’s Yucatan Peninsula, a keen eye may notice that although it is located in the tropics, and therefore receives quite a bit of rain in its wet season, there are no major lakes or rivers to speak of, especially to the north.  There is water there, though, flowing underground through aquifer and cave systems known as cenotes.

Since Mayan times, people living in the Yucatan have relied on the cenotes as their source of drinking water.  Growing population in the region have obliged the government to make environmental assessments of the area, and that hydrological surveys of the cenotes.  As a result, the full extent of these underground water systems are becoming apparent.  Two of the systems in the region – Ox Bel Ha and Sac Actun – trade the title of the longest underground river in the world, each having over 180km of explored passageways. You can see an older map of Ox Bel Ha at the site of the group who did the first explorations.

Exploring a cenote, image from Cave-Exploration.com

Exploring the cenotes combines the dangers of diving with the challenges of caving.  The air in their tanks limit how long they can remain in the cave at one time, and the dark, narrow passages give many chances to become lost or stuck.

Exploring a cenote, image from Cave-Exploration.com

The explorers have found numerous relics in the caves, some supposed to be significantly older even than the Mayan culture, perhaps as old as 9,000 years.  They are thought to have been the centre of religious traditions in the area, with the Sacred Cenote of Chichen Itza possibly the site of human sacrifices to their rain god Chaac.

The cenotes have a connection to an even earlier history than that, far earlier than anything from human history.  In the north of the peninsula, many of the cenotes form a distinct ring, following the rim of the Chicxulub crater, the site of an asteroid impact from some 65 million years ago, and a candidate for the cause of the great dinosaur extinction.

Prehistoric geology, ancient human rituals, the encroachment of modern society.  Could the Mayans have been sacrificing not so much to a god in the skies as to a predator under their feet?  A predator that has been there for millions of years.  Shades of Colour out of space, perhaps.