Indiana Jones would not want to explore this cave, where snakes hang from the ceiling, waiting to snag bats from the air for dinner.

Near the town of Kantemó in southern Mexico’s Yucatan Peninsula, the cave is a growing destination for adventurous ecotourists. About 300 visitors enter the cave a year, hoping to get a glimpse of the unusual behavior, says Liliana Garcia Ramirez, the director of Amigos de Sian Ka’an, a local nonprofit.

The yellow-red rat snakes (Pseudelaphe flavirufa) are not venomous, Ramirez says, and, as fierce as they look, they aren't a threat to people.

Typically, the relatively small serpentsy prey on rodents, lizards, and other small animals on the ground, in forests. But over time, some