The skeleton of an eighteen-year-old girl lies legs akimbo on the cave floor, two of her vertebrae crushed. She is known as the Crystal Maiden, and after a thousand years, she has newfound celebrity.

Discovered in 1989, this jungle cave in the Tapir Mountain Nature Reserve is accessible via an hour’s ride from San Ignacio, Belize, and a walk for another hour across shallow rivers and through jungle. Here one arrives at the Actun Tunichil Muknal or “ATM” cave mouth. To gain access to the cave one must swim in and then wade up the cave river for another kilometer.

Walking a further kilometer and a half in the cave, past huge boulders and cavernous rooms (one known as “The Cathedral”), to the back of the cave system, you find the skeletons of the ritual sacrifices made by the Maya to their Gods, more than a thousand years ago.

The skeletons range in age from one year old to adult. Four of those sacrificed are infants between the ages of one and three, some of them stuffed into crevices and small adjoining caves. There is one child of seven, a teenager of fifteen who appears to have been bound before being killed, a twenty-year-old, and the rest are adults between the ages of thirty and forty-five. Many of the younger skeletons show signs of cranial deformation or “skull shaping,” giving their heads a slightly elongated alien look.

Almost all were killed by blunt trauma to the head, with some having had their entire skulls crushed. While the precise dating of the skeletons is difficult (due to their being essentially cemented to the cave floor by calcite) most of the pottery found at the site dates from between 700 and 900 AD, which is likely when the bodies found here were sacrificed.

Farther into the cave is perhaps the most famous of these long-dead Maya, the skeleton of an eighteen-year-old girl (or one thousand and eighteen years old, at this point) known as the “The Crystal Maiden.”

She is unique in her positioning and the fact that two of her vertebrae are crushed. Because of this researchers believe she may have died in a particularly violent manner and then been thrown or tossed onto the ground, where she has lain for at least the last 1,100 years. The skeleton has been there so long, in fact, that it has been completely calcified, giving her bones a sparkling, slightly plump look and inspiring the name “The Crystal Maiden.”

It is unknown what the circumstances of the sacrifices were, though some believe they were to appease the rain god Chac, or possibly the gods of the underworld. Another theory holds that these were believed to be witches (possibly suffering from some kind of mental or physical ailments) and that leaving them unburied in the cave would ensure that their spirits were trapped there.

Other items found in the cave include ceramics, marked with “kill holes,” and cave formations carved by the Maya, such as silhouettes of faces and animals. The cave is also home to Amblypygi or “whip spiders” and other predatory spiders.

Due to the inaccessibility and the calcification process of the cave, many of the relics have been preserved just as they were left and very little has been removed from the cave since it was discovered. (Some things were looted early on.)

The name Actun Tunichil Muknal translates as “Cave of the Crystal Sepulchre,” and the locals know it as “Xibalba” after the Mayan underworld. The Crystal Cave was traditionally believed to be an entrance to hell, a deep fissure in the earth filled with rivers of blood and scorpions. This was the domain of the Mayan death gods, the subterranean court of the “Lords of Xibalba.” Often referred to as demons, these twelve deities had names like “Stabbing Demon” and “Skull Staff,” and inflicted a range of maladies on people including sickness, pain, and fear.

In a country not known for protecting its cultural heritage, ATM cave is one of the few protected places, with only a few guides authorized to lead tours of the cave. Be very careful, however, as none of the skeletons or pottery are roped off, and one tourist has already accidentally stepped on and broken one of the skulls.