You've heard the saying "There's nothing new under the sun."

Explorer and NGS/Waitt grantee Sam Meacham has a suggestion: Go underground.

Beneath the jungles of the Yucatan peninsula, Meacham and his team are exploring and mapping the longest underwater cave system in the world.

This year, the team of six divers—Alejandro Alvarez, Franco Attolini, Fred Devos, Christophe Le Maillot, Daniel Riordan, and Meacham—explored Sistema Ox Bel Ha, the seventh longest cave on Earth, all of it underwater. Working one week per month from January to June, they were able to explore and map more than 39,000 feet (12,000 meters) of new passageways, pushing the system beyond 112 miles (180 kilometers) in total length.

The system is an important source of freshwater for the region. But human development at the surface risks polluting the aquifer. Meacham hopes that by mapping the caves, his team can encourage more sustainable development above by showing the relationship with the caves below..

The project also has broad relevance to the sciences. Team members return with organisms that could be new species, core samples that help climatologists develop a record of environmental changes over time, and observations that are of interest to hydrologists and even archaeologists studying the ancient Maya.

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