Cave divers and drones test a new theory of how water moves under the Yucatán Peninsula

The Yucatán Peninsula's cenotes and flooded caves may be only the visible edges of a far larger water system. That is the idea behind Project MAYAS, a research effort led by the cave explorer and diver Robbie Schmittner, which Mexico's National Commission of Natural Protected Areas (Conanp) said on November 3 it is supporting. The project proposes that the most extensive underground rivers and flooded cave systems known are, to a large degree, secondary features of a bigger hydraulic network whose main channels have barely been explored.

The peninsula holds Ox Bel Ha and Sac Actun, which Conanp describes as the two most extensive systems of underground rivers and flooded caves known in the world. Around 2,000 kilometers of underwater passages have been explored and mapped in the region, according to the commission. Under the MAYAS hypothesis, large parts of those systems, including long sections of both, are secondary features of the larger network.

Where the project is looking

Conanp names six large geological structures that the project thinks could steer the region's groundwater, and says the research will test how they connect. The project's own website speaks of verifying five major fracture systems; the two counts are as each source gives them.

• Anillo de Cenotes (the Ring of Cenotes)
• Sierrita de Ticul
• Río Hondo
• Holbox
• Akumal
• Arco de La Libertad

The project also proposes what drives the water. Its hypothesis is that the current and pressure conditions created by the strong sea currents in the Yucatán Channel, between the Caribbean and the Gulf of Mexico, are the main force moving groundwater across the region. Conanp says the idea will be tested with research and field measurements.

How the work is done

The project works on three levels, Conanp says. Drones carrying geophysical instruments take measurements from the air to find hidden fracture zones, possible caves and groundwater routes. Teams on the ground then follow those leads, examine the rock structures and look for cenotes and other natural entrances. Specialist underwater cave explorers map the flooded passages, measure flow, currents and water quality, and collect samples for analysis of DNA, algae, bacteria and other life.

The project's website describes the same approach and adds LiDAR mapping and thermal analysis to the airborne work. It says Schmittner has explored the water-filled caves along the Caribbean coast for more than three decades, and that with support from Rolex, 2026 marks the project's move into full-time research.

Why it matters to visitors

Conanp ties the research to tourism, among other activities. It says tourism, farming, fishing and many other activities depend on healthy ecosystems and reliable water, and that pollutants can travel long distances through groundwater and harm ecosystems far from where they entered it. The project's findings, it says, should help explain those pathways, identify vulnerable zones and give a scientific basis for protection measures. Results are to be shared through scientific publications, work with authorities and conservation bodies, and educational activities for schools, universities and the public.

The work is not limited to the peninsula: it extends to Veracruz and other parts of southern Mexico, and Belize and Guatemala are planned for the long term. Conanp says the project is backed by the Rolex Perpetual Planet Initiative and by Germany's honorary consulate in Mexico, and works with universities, research centers and federal bodies including the national archaeology institute (INAH) and Conanp itself. Conanp's release mentions no change to visitor access at any cenote or cave, and it gives no timetable for results.