Scientists Discover World's Longest Underwater Cave In Mexico

Mexico is well-known for its cenotes - which are underwater caves, usually jump-in-able and swimmable. They're a big attraction all across the country for tourists and locals alike.

Credit: CEN

Now the country has an extra jewel in its crown after the discovery of the world's longest underwater cave - at 347 kilometres (216 miles) - in the Mexican state of Quintana Roo.

But it's not just the size that matters. The newly-discovered cavern hosts a wealth of architectural treasures, not least because researchers from the Gran Acuifero Maya (GAM) Project discovered a tunnel connecting two large underwater caverns.

The fact that the cave systems of Sac Actun and Dos Ojos are connected means that they combine to create the world's largest cavern.

Robert Schmittner, the director of GAM - which is a multidisciplinary organisation based in Mexico City and which is part of the National Institute of Anthropology and History (INAH) - said that it took 14 years of research, exploration and analysis to uncover the connection between the two aquatic labyrinths.

The time and effort paid off, though. INAH investigator Guillermo de Anda called the discovery "the most important underwater archaeological site in the world and home to hundreds of preserved secrets."

Anda added that the cave 'contains evidence of the first American civilisations, extinct fauna and Mayan culture'.

The previous longest explored underwater cave in the world was the Ox Bel Ha system, which is also located in Quintana Roo and located south of Tulum, whose underwater passages measured a still staggering 270.2 kilometers (167.9 mi).

At first, it was thought that this new tunnel network was around the same length, but the discovery of the connecting tunnel between the two caves means that it's much longer.

And it's not just long, but also deep - the cave has an average depth of 20 kilometres (12.4 miles) - Jesus Christ! - but there are areas that are much more shallow, between two and 100 metres.

You wouldn't catch us going in there though. We've seen The Descent. We'll leave that to the archaeologists who get paid to do that stuff.