For years, villagers who lived near the Sac Uayum sinkhole in Mexico's Yucatán peninsula refused to go near it, calling the underwater cave haunted. Turns out, they had good reason to be scared.
Explorers from National Geographic sent to probe the natural well found a creepy surprise beneath the sinkhole's surface: chambers littered with human bones.
Located south of the modern-day city of Mérida, the sinkhole (also known as a cenote) was once positioned just outside the ancient Maya city of Mayapán, according to National Geographic. Experts believe the bones found in it belong to locals who were given a watery burial following an epidemic or similar tragedy.
"Suppose these were plague victims," archaeologist Bradley Russell told National Geographic. "You wouldn't want them near the rest of the population. And you wouldn't want to drink the water either."
Cenotes are scattered across the Yucatán and are popular tourist attractions, according to the Travel Channel. But back in the day they are believed to have held special ritual significance for the Maya people, who controlled the region until the 10th Century.
The bones found south of Merida aren't the only such find. In 2011 researchers discovered the bones of six people in a cenote near the ancient Maya city of Chichén Itzá. The remains appeared to be evidence of human sacrifices dating back to between the years 850 and 1250, National Geographic reported.
That discovery reinforced the theory that the Maya considered cenotes to be "thresholds of communication with the spiritual and sacred world that lay under the surface of the Earth," Guillermo Anda, a professor at the Autonomous University of Yucatán, told the magazine.
Unlike the Chichén Itzá remains, however, the bones scattered throughout Sac Uayum are not considered evidence of ritual sacrifice.