The bedrock here is comprised of thick limestone, a rock that gives way to erosion more easily than most, particularly when the water is acidic. This calcareous platform formed 66 million years ago when life within a shallow sea died off and was ultimately lithified. Eventually, this huge, porous, limestone platform began to be eroded by the somewhat acidic rainfall, which ate away at the underlying rock, forming these underwater caves.
The sea levels eventually dropped, which caused parts of the limestone roof to collapse in on themselves, giving us cenotes. The sea levels then eventually rose again, and the caves flooded.
“This huge cave represents the most important submerged archaeological site in the world,” Guillermo de Anda, researcher at the National Institute of Anthropology and History and director of the GAM, added.
Apart from the wealth of archaeological artifacts hidden within the caves, he also explains that this giant cave “gives rise to and supports a great biodiversity.”
“Now everyone's job is to conserve it,” Schmittner concludes.