The oldest skeleton in the Americas was discovered in the world's biggest underwater cave - but the site is now under threat

PBS First Face of America

Alberto Nava

Archaeologists have found countless artifacts deep within the Sac Aktun cave - but now it's under threat.

  • The Sac Aktun cave system holds artifacts stretching back 15,000 years, including preserved remains of Ice Age megafauna to Mayan artifacts.
  • It was recently discovered to be the largest underwater cave system in the world.
  • The cave is one of the world's most important underwater archaeological sites, but it's under threat from pollution and development.

One of the world's largest and most important underwater archaeological sites is under threat from pollution and development.
The recently mapped Sac Aktun cave system on Mexico's Yucatan Peninsula was recently discovered to be the largest underwater cave in the world at 216 miles long. It contains some of the oldest human remains ever found in the Americas, as well as countless other artifacts stretching back over 15,000 years.

"I think it's overwhelming. Without a doubt it's the most important underwater archaeological site in the world," Guillermo de Anda, an archaeologist at Mexico's National Anthropology and History Institute who is leading excavations in the cave told The Associated Press.

PBS First Face of America

Francis Cordero Ramirez

This remarkably intact skeleton was found in the cave, and it's helping researchers shine a light on how the earliest Americans lived.


A remarkably intact, 13,000 year-old skeleton found in the cave in 2007 is one of the oldest examples of human remains in the Americas, and provided a crucial window into how America's earliest inhabitants lived, migrated, and died. The skeleton was recently the subject of a NOVA documentary.

Researchers have also identified over 120 sites inside the cave that are filled with Maya-era pottery and bones from over a thousand years ago. They've also discovered bones of long-lost Ice Age megafauna like giant sloths, proto-elephants, and extinct bear species, the AP reports. The cave has undergone periods of flooding and drought throughout history, and has been used for thousands of years by people searching for water and shelter in periods of "great climate stress," de Anda told the AP.

Unfortunately, increased pollution and acid runoff from nearby development are threatening the pristine cave.

The cave is connected to 248 cenotes, which are used for snorkeling and swimming by an increasing number of tourists. A major highway to the Mexican state of Quintana Roo also runs above the cave system. During periods of intense rainfall, the highway has collapsed into sinkholes, the AP reports.

Researchers have also found elevated acidity levels in the cave, likely due to runoff from a nearby dump. That acidity can degrade skeletal remains over time.