Tulum's Hoyo Negro cave and its ancient skeleton anchor a new INAH research agreement

INAH and the cave-diving group CINDAQ signed an agreement, announced on August 17, that puts underwater archaeology in Quintana Roo on a formal footing after two decades of work in its flooded caves and cenotes.

The document was signed by the institute's Subdirección de Arqueología Subacuática (SAS) and covers cave and cenote exploration, archaeological documentation, conservation of recovered objects, exchange of information, and public education.

Almost everything Mexican archaeology knows about the first people on the Yucatán Peninsula came out of caves that filled with water at the end of the last ice age. INAH does not maintain a cave-diving team of its own. For twenty years, getting into those chambers has depended on the divers who now have a contract.

Quintana Roo sits on limestone with no surface rivers. Rain drains through the rock into flooded galleries that run for hundreds of kilometers, and two of the longest mapped systems in the world, Ox Bel Ha and Sac Actun, both lie in the Tulum area. Those galleries were dry ground when the first people walked into them. That is the only reason the archaeology is down there at all.

The divers who reach what INAH cannot

Silvina Vigliani, the SAS researcher who leads the project "Prehistoria de la península de Yucatán a través de sus evidencias en cuevas y cenotes," said the CINDAQ team has been essential in accessing environments that would otherwise remain hidden. What the group supplies is technical and unglamorous: cave diving expertise and training, equipment, expedition logistics, topography, photogrammetry, photography and the handling of digital data.

They also hand over what they map. In a karst system, a survey line is the difference between a documented site and a rumor about a chamber somebody once saw.

CINDAQ's dive team has logged more than 15,000 dives in the state's underground rivers and has over 70 years of combined experience, according to the organization. It is accredited as a non-governmental organization under the 2001 UNESCO Convention on the Protection of the Underwater Cultural Heritage and recognized by the Nautical Archaeology Society in the United Kingdom.

The formality matters more than it sounds. Anything archaeological inside those caves is federal property under Mexican law, and only INAH can authorize work on it. A civil association cannot recover an artifact on its own initiative, no matter how good its divers are. Roberto Junco Sánchez, who heads the SAS, said the agreement formalizes a working relationship built over more than two decades.

Hoyo Negro, under study since 2011

The clearest product of that relationship sits inside a pit near Tulum. The Hoyo Negro underwater archaeological project began in 2011 and is still running.

The pit holds the bones of Pleistocene animals and human remains, among them Naia, a teenage girl whose skeleton is one of the oldest and most complete recovered anywhere in the Americas. Researchers have placed her age at roughly 12,000 to 13,000 years. In 2023, UNESCO awarded the project a best-practice distinction for its approach to studying and protecting the site.

An ochre mine 10,000 years down

In 2017, CINDAQ divers mapping new tunnels in the Sagitario system found cut walls, dug pits and charcoal. A study published in Science Advances in July 2020 identified the place as a prehistoric ochre mine and dated the digging to between roughly 10,000 and 12,000 years ago, the oldest known in the Americas.

The finding changed the question. The caves were not only places where people sheltered or fell in. People went down there to work, carrying fire, and then the sea rose and sealed the entrances behind them.

Underwater archaeology in Quintana Roo enters a national atlas

Among the projects that stand to gain from the agreement is the Atlas Arqueológico Subacuático de Cenotes, Cuevas Inundadas y Semiinundadas y Otros Cuerpos de Agua Continentales de la República Mexicana, directed by archaeologist Helena Barba Meinecke. It is a national inventory, and Quintana Roo supplies a large share of it.

The collaboration has also moved inland. At Chichén Itzá and Ek' Balam, the teams produced aerial maps, digital models and panoramic imagery that specialists use for study and conservation work above the waterline.

One name kept coming up at the signing

Sam Meacham, CINDAQ's director, credited Pilar Luna Erreguerena, the archaeologist who built INAH's underwater archaeology department and died in 2020. "Her vision, openness and trust helped establish the foundations of the collaboration with CINDAQ," he said.

The announcement did not name which sites go first under the new agreement, or how long it runs. Hoyo Negro's work continues either way, and the atlas still has to be filled in cave by cave, by people who can find their way back out.

Should more of Quintana Roo's flooded caves be opened to research, or kept closed to protect what is inside them? Join the conversation and share your perspective with us on Instagram and Facebook at @thetulumtimes.