Mexico Plans a 6-Million-Acre Underground Reserve in Yucatán

Mexico’s federal government is drawing up a protected area that would sit almost entirely underground, covering the rivers, caves and basins beneath the Yucatán Peninsula.

If it goes through, the reserve would be nearly 12 times the size of Yucatán’s Ring of Cenotes reserve. That’s about 6.2 million acres, compared with the roughly 528,000 acres the state reserve covers today. For now, though, only the paperwork is moving.

Pedro Álvarez Icaza, head of the National Commission of Natural Protected Areas (CONANP), said the technical study needed to justify the decree is 80% complete. The area would stretch across Yucatán, Campeche and Quintana Roo. He noted that progress on the study does not mean protection has been approved.

Mapping What Can’t Be Seen

Drawing the boundaries is the hard part. Planners must account for underground basins and rivers as well as everything happening on the surface above them. Álvarez Icaza said mapping the region’s karst caves poses highly complex challenges.

To make the plan work, environmental authorities are developing a new category under Mexico’s main environmental law, the General Law of Ecological Balance and Environmental Protection, designed for underground basins and rivers. It is not yet clear whether that will require a legal reform.

The timeline has two steps. CONANP expects to publish its findings and open a public consultation before the end of 2026, with a formal decree projected for 2027.

This is not the first target date. In May 2025, Álvarez Icaza said he hoped to present a declaration that year, starting with Playa del Carmen, then the rest of Quintana Roo and eventually Yucatán. The scope has since grown to the whole Peninsula, and the goal has moved to 2027.

He acknowledged that the reserve has to coexist with infrastructure, farming and tourism above ground. He said the aim is not to stop surface development but to protect what lies beneath.

Why It Matters in Yucatán

Groundwater is the only water source for virtually everyone in Yucatán state. The aquifer sits in highly permeable limestone linked by cenotes, cracks and caverns so that pollution can travel fast. Researchers at the Autonomous University of Yucatán (UADY) note that the state’s Sustainable Development Secretariat has registered 3,050 cenotes, out of an estimated 7,000 to 8,000.

Academic studies estimate that 71% of the aquifer is highly, very highly or extremely vulnerable and that only 2.7% of wastewater is treated. Those numbers help explain the state’s broader struggles with water management.

The Ring of Cenotes shows that a decree is only a beginning. The state reserve was created in 2013, but the government took about a decade to put its management plan out to bid. A July 2025 decree raised the number of municipalities covered from 13 to 24, even as the protected area shrank slightly.

Environmental groups say the ring actually crosses far more municipalities than that. A 2020 Greenpeace Mexico report counted 43 pig farms inside four protected areas in Yucatán, including the Ring of Cenotes. Maya residents near Homún have even asked courts to grant the cenotes legal personhood.

Money and Missing Pieces

Álvarez Icaza said CONANP’s budget should rise 25% next year to roughly MX$1.7 billion (about US$93 million), after a 50% increase the year before. The agency manages 232 federal protected areas covering 98 million hectares (about 242 million acres). He did not say how much would go to the new reserve.

The proposal was developed with civic groups, cave explorers and cave divers, and earlier studies were done with Semarnat, Mexico’s environment ministry, and hydrology specialists. Working groups will help set boundaries and land-use rules.

The role of Maya communities living above the aquifer remains unclear. Reports mention a public consultation, but not a specific consultation with Indigenous communities. The full study, draft boundaries, the new legal category and a detailed consultation calendar have not yet been published.

Fast Facts

• Proposed area: About 2.5 million hectares (6.2 million acres), underground
• States covered: Yucatán, Campeche and Quintana Roo
• Agency: National Commission of Natural Protected Areas (CONANP)
• Study progress: 80% complete, according to CONANP
• Next step: Findings and public consultation expected before the end of 2026
• Decree target: 2027
• Ring of Cenotes reserve today: about 528,000 acres in 24 municipalities
• Registered cenotes in Yucatán: 3,050 of an estimated 7,000 to 8,000

With reporting from Por Esto! and The Associated Press