Located just off of the famous Route 66 in New Mexico’s arid climes is the Santa Rosa Blue Hole, a natural swimming hole that has a hidden system of underwater caves which were unexplored until 2013.

Like many natural pools of its kind, the Santa Rosa Blue Hole is a small body of water that seems to fill a surprisingly deep hole in the ground with shockingly clear waters. During the heyday of road-tripping families cruising down Route 66, the swimming hole was a popular oasis in the unbroken desert. The deep hole was also a favored spot for scuba divers until two young divers became trapped in the pool’s tight underwater caves. After their deaths in 1976, the entrance to the caves was covered with a metal grate and all but forgotten.

However, in 2013 a group of adventurous divers with ADM Exploration Foundation were allowed past the grate with the intention of mapping the system of unexplored caves. Their initial probing was stymied by decades of debris and too tight passages but the excavation continues with a careful eye towards safety lest further deaths close off the mysterious caverns for decades to come. It’s still unclear how far back the caves go.