Sistema Sac Actun


Sistema Sac Actun is an underwater cave system situated along the Caribbean coast of the Yucatán Peninsula with passages to the north and west of the village of Tulum. Discovery of a connection to the Sistema Dos Ojos in 2008 made it the longest known underwater cave system.
The remains of a mastodon and a human female that might be the oldest evidence of human habitation in this area to date have been found in the cave.

History of exploration

Exploration started from Gran Cenote west of Tulum. The whole of the explored cave system lies within the Municipality of Tulum.
In early 2007, the underwater cave Sistema Nohoch Nah Chich was connected into and subsumed into Sac Actun making it the longest surveyed underwater cave system in the world.
Sac Actun measured and is as of May 2017 with an explored length of only surpassed by Sistema Ox Bel Ha at. Since early 2007, these two caves frequently exchanged the title of the longest Quintana Roo Speleological Survey underwater cave system in the world. Including connected dry caves makes Sistema Sac Actun with the longest cave in Mexico and the second longest worldwide.
In 2018, the discovery of a link between the Sac Actun system and the Dos Ojos system in Tulum, Quintana Roo was reported. The connection was found by the Gran Maya Aquifer Project, led by the cave diver and explorer, Robbie Schmittner. The combined system is reported to be the world's largest underwater cave system known.

Upper Paleolithic remains

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 known as the pit Hoyo Negro. At a depth of the divers located the remains of a mastodon, as well as at a human skull that might be the oldest evidence of human habitation in this area. Additional bones were located and the skeleton was later identified as that of a teenage female now referred to as Naia.