San Actun may be the newest household name for divers and historians. Divers from the Gran Acuifero Maya began exploring this collection of underwater tunnels ten months ago and have discovered over 200 interconnected caves. For those unfamiliar with diving, picture a gigantic, underwater version of a landscape you might find in an Indiana Jones flick — that also happens to be teeming with ancient history.

Off the coast of the Yucatan Peninsula in the Mexican state of Quintana Roo, archaeologists say that there are 216 miles of connected tunnels that make up San Actun, landing the system an impressive title: the world’s largest underwater cave. Scientists note that the Mayans may have thought of such a system as a gateway to the underworld. Bones and other signs of human presence have been discovered, potentially offering an important glimpse into life in the region nearly 1,500 years ago. GAM’s director, Guillermo de Anda, explained to Reuters: “It allows us to appreciate much more clearly how the rituals, the pilgrimage sites and ultimately the great pre-Hispanic settlements that we know emerged.”

Have a look for yourself!