Cenote

A cenote (English: /sɪˈnoʊti/ or /sɛˈnoʊteɪ/; Latin American Spanish: [seˈnote]) is a natural pit, or sinkhole, resulting when a collapse of limestone bedrock exposes groundwater.

The term originated on the Yucatán Peninsula of Mexico, where the ancient Maya commonly used cenotes for water supplies, and occasionally for sacrificial offerings.

[4] Cenotes are common geological forms in low-altitude regions, particularly on islands (such as Cefalonia, Greece), coastlines, and platforms with young post-Paleozoic limestone with little soil development.

[8] Cenotes are formed by the dissolution of rock and the resulting subsurface void, which may or may not be linked to an active cave system,[clarification needed] and the subsequent structural collapse.

The stereotypical cenotes often resemble small circular ponds, measuring some tens of meters in diameter with sheer rock walls.

In the north and northwest of the Yucatán Peninsula in Mexico, the cenotes generally overlie vertical voids penetrating 50 to 100 m (160 to 330 ft) below the modern water table.

Where a cenote, or the flooded cave to which it is an opening, provides deep enough access into the aquifer, the interface between the fresh and saline water may be reached.

[citation needed] Flora and fauna are generally scarcer than in the open ocean; however, marine animals do thrive in caves.

[12] In 2001–2002 expeditions led by Arturo H. González and Carmen Rojas Sandoval in the Yucatán discovered three human skeletons; one of them, Eve of Naharon, was carbon-dated to be 13,600 years old.

[13][14][15] In March 2008, three members of the Proyecto Espeleológico de Tulum and Global Underwater Explorers dive team, Alex Alvarez, Franco Attolini, and Alberto Nava, explored a section of Sistema Aktun Hu (part of Sistema Sac Actun) known as the pit Hoyo Negro.

Major Maya settlements required access to adequate water supplies, and therefore cities, including the famous Chichen Itza, were built around these natural wells.

Edward Herbert Thompson (1857–1935), an American diplomat who had bought the Chichen Itza site, began dredging the Sacred Cenote there in 1904.

In Mexico, the Quintana Roo Speleological Survey maintains a list of the longest and deepest water-filled and dry caves within the state boundaries.