What is a Cenote?
What is a Cenote?
How many cenotes are there, how do they form and what purpose did they serve?
Cenotes (say-No-tays) are natural pits, or sinkholes, resulting from the collapse of limestone bedrock that exposes groundwater. The regional term is specifically associated with the Yucatán Peninsula of Mexico, where cenotes were commonly used for water supplies by the ancient Maya (and occasionally for sacrificial offerings, but thankfully not anymore!). The term derives from a word used by the lowland Yucatec Maya — tsʼonot or dzʼonot — to refer to any location with accessible groundwater.
There are estimated to be over 7,000 cenotes in the peninsula and they have become popular tourist attractions. Many are extremely photogenic and cenote water is often very clear, due to the water coming from rain water filtering slowly through the ground and therefore containing very little suspended particulate matter.
Cenotes form when limestone bedrock dissolves, resulting in a void under the surface and subsequently the structure collapses. It is likely that the rate of collapse increases during periods when the water table is below the ceiling of the void, since the rock ceiling is no longer buoyantly supported by the water in the void. In their formation, the depth of contact between deep salt water and surface fresh water (called halocline) also plays a fundamental role.
Check out this excellent 90 second video by Ocean Wise about Cenote formation.
Cenotes may be fully collapsed, creating an open water pool, or partially collapsed with some portion of a rock overhanging above the water. The stereotypical cenotes in the state of Yucatan often resemble circular ponds, measuring some tens of meters in diameter with sheer rock walls. These are typical around the site of the Chicxulub impact crater. In contrast however, the 'Riviera Maya', from Puerto Morelos to Tulum on the Caribbean coast of the peninsula (state of Quintana Roo), features more cenotes that are shallow collapsed cave systems with wide and branched galleries filled with stalagmites and stalactites.
Of the 7,000+ cenotes, most require some degree of stooping or crawling to access the water, however many of the more accessible ones have become popular tourist destinations. As well as swimmers and snorklers, the cenotes along the Quintana Roo coast attract cavern and cave divers, keen to explore the extensive and elaborately decorated flooded caves.
Extensive underwater systems have been documented, including the world's longest known underwater cave; following the discovery of a link between the Sistema Sac Actun (reported to be 263 km long) and the Sistema Dos Ojos in Tulum, Quintana Roo (84 km long).
It should be noted that venturing out of the air/light zone of any cenote can be very dangerous and only experienced and qualified cave divers should attempt any such exploration without a guide.
