Locals refer to it as Sac Uayum, a flooded sinkhole in southern Mexico that they don't dare enter, or even step foot near. Located just outside the ruins of the ancient Maya city Mayapan, the natural well was said to have been feared even by the Mayan people, and villagers still to this day believe that a giant child-eating serpent, with a horse's head, guards the cavern. Though such stories are of course nothing more than urban legends, designed to keep people away from the sinkhole, the truth isn't actually all that much less frightening than the stories.
As reported by National Geographic, archaelogist Bradley Russell and his team bravely ventured inside the allegedly haunted cavern this past August, and spent two weeks exploring it. While no such serpent was found inside, Russell did discover that the floor of the underwater cavern was littered with human bones, including the skulls of 15 different human beings. Also included among the remains are cattle bones, which Russell believes are the result of the animals venturing too close to the sinkhole, and falling down to their death.
Though Russell isn't entirely sure what the explanation is for the human remains, he does have one theory that seems to make a whole lot of sense. "Suppose these were plague victims," says Russell. "You wouldn't want them near the rest of the population."
Or, perhaps, the horse-headed serpent really does exist, and the remains are those of his many victims...