The discovery has experts wondering whether Maya legend inspired the construction of the underground complex—or vice versa.
According to Maya myth, the souls of the dead had to follow a dog with night vision on a horrific and watery path and endure myriad challenges before they could rest in the afterlife.
In one of the recently found caves, researchers discovered a nearly 300-foot (90-meter) concrete road that ends at a column standing in front of a body of water.
"We have this pattern now of finding temples close to the water—or under the water, in this most recent case," said Guillermo de Anda, lead investigator at the research sites.
"These were probably made as part of a very elaborate ritual," de Anda told National Geographic News in August. "Everything is related to death, life, and human sacrifice."
Read about the watery graves of the Maya in National Geographic magazine.
Full text: NGM