Divers made the find while exploring the Sac Actun cave system in the Mexican state of Quintana Roo 

They have discovered 200 archaeological sites in the cave system, near the beach resort of Tulum

Around 140 are from the Mayan culture that dominated large parts of the Americas until the 9th century AD

Experts also found bones of giant sloths, ancient elephants and extinct bears from the Pleistocene period