A prehistoric human skeleton has been found in a cave system that was flooded at the end of the last ice age 8,000 years ago, according to a cave-diving archaeologist on Mexico’s Caribbean coast.

Researchers have found bones from animals that roamed the world during the last Ice Age and ancient human remains that date back at least 9,000 years in Mexico’s largest flooded cave.

Divers from the Great Mayan Aquifer project (L) are in the underwater Sac Actun cave system near Tulum, Mexico, looking for Mayan and Pleistocene bones and cultural objects that have been discovered there. (Source: GAM/INAH)

The world’s largest flooded cave was recently revealed by a group of divers connecting two underwater caves in eastern Mexico; this finding may help shed new light on the ancient Maya civilization.

The Yucatan peninsula is covered in enormous Maya artifacts, whose towns rely on a vast network of sinkholes connected to underground water sources known as cenotes.

Remains of a mask in the Sac Actun underwater cave in Mexico’s Quintana Roo state. [Credit: GAM/INAH]

Near the seaside town of Tulum, in the 347-km (216-mile) long Sac Actun cave system, researchers claim to have discovered 248 cenotes. There are 200 archaeological sites in total, and 140 of them are Mayan.

The Maya, whose descendants still live in the area, gave some cenotes special religious significance.

Remains of a Pleistocene bear from 2.5 million years ago, in the Sac Actun underwater cave in Quintana Roo state, Mexico [Credit: GAM/INAH]

The Pleistocene era bears, enormous sloths, and ancient elephants’ bones were also discovered, according to a statement from Mexico’s Ministry of Culture.

The cave’s discovery has rocked the archaeological world.

Researchers from Mexico’s National Institute of Anthropology and History (INAH), say they have discovered200 archaeological sites in the cave system [Credit: GAM/INAH]

“I think it’s overwhelming. Without a doubt it’s the most important underwater archaeological site in the world,” said Guillermo de Anda, a researcher at Mexico’s National Anthropology and History Institute (INAH).

De Anda also serves as the project’s director, the Gran Acuifero Maya (GAM), which aims to research and protect the Yucatan peninsula’s underground waterways.

The INAH claims that the cave system was flooded towards the end of the Ice Age when water levels rose by 100 meters, creating “ideal conditions for the preservation of the remains of extinct megafauna from the Pleistocene.”

The most recent Ice Age, known as the Pleistocene geological epoch, lasted from around 11,700 years ago to 2.6 million years ago.