Paleontology
In 2001–2002 expeditions led by Arturo H. González and Carmen Rojas Sandoval discovered three human skeletons; one of them, Eve of Naharon, was carbon dated to be 13,600 years old. 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. At a depth of 57 meters (187 ft) the divers located the remains of a mastodon as well as at 43 meters (141 ft) a human skull that might be the oldest evidence of early man in this area to date.
Read more about this topic: Cenote