Mexico ’s outgoing leader has built a train system looping around the country’s southern peninsula, connecting tourist hubs like Cancún and Playa del Carmen to dense jungle and remote archaeological sites. The line is designed to draw money into long-neglected rural swathes of the country. But the crown jewel of the populist’s presidency also runs over one of Mexico’s natural wonders: A fragile system of an estimated 10,000 subterranean caverns, rivers, lakes, and freshwater sinkholes.
The cave system contains one of the biggest aquifers in Mexico and acts as the region’s main water source, crucial at a time when the nation faces a deepening water crisis. The region was once a reef nestled beneath the Caribbean Sea, but changing sea levels pushed Mexico’s southern peninsula out of the ocean as a mass of limestone. Water sculpted the porous stone into caves over the course of millions of years.
It produced the open-face freshwater caverns known as “cenotes” and underground rivers that are in equal parts awe-inspiring and delicate, explained Emiliano Monroy-Ríos, a geologist at Northwestern University studying the region. “These ecosystems are very, very fragile,” Monroy-Ríos said. “They are building upon a land that is like gruyere cheese, full of caves and cavities of different sizes and at different depths.
” The train has sparked criticism by environmentalists and scientists as its construction plowed down millions of trees, a chunk of the large.
