The tiny Central American-Caribbean nation of Belize is a caver’s delight: miles and miles of underground tunnels and caverns to explore. Actun Tunichil Muknal, one of Belize’s most spectacular caves, was featured in the 1993 National Geographic Explorer film Journey through the Underworld: its name means “Cave of the Crystal Sepulchre.”

To get to the cave entrance, visitors are first required to hike for forty-five minutes through beautiful but dense jungle: there are three tricky river crossings thrown in for good measure. Access to the cave is gained by a short, refreshing swim through a small blue pool, after which hard hats and lights are needed to negotiate the cave system. It is also possible to repel into this underground labyrinth. Actun Tunichil Muknal is a registered archaeological site and only specially trained guides are allowed to lead groups into the cave—there are no do-it-yourself possibilities here. Besides, entering this dark maze on your own would be suicidal.  

Actun Tunichil Muknal was re-discovered in 1986 by archaeologist Thomas Miller. What he found was astonishingly well-preserved Mayan pottery and the skeletal remains of several humans, who appear to have been sacrificed. To date, a total of fourteen individual skeletons have been identified. The most remarkable aspect of this cave tour is that most of these Mayan artefacts are still in place for visitors to enjoy. In fact, visitors are allowed to get so close to these pieces that guides have to be very strict about where people can walk. Although some parts of the cave have been looted, the entrance to the main chamber is not obvious and was left untouched throughout the centuries. Fear of spirits also keeps some would-be looters at bay.

After wading through knee- or even chest-deep water, negotiating small crevices and carefully scrambling up ladders, the tour culminates in the dramatic site of the preserved skeleton of a 20-year-old Mayan woman, “The Crystal Maiden,” lying below a rock wall. Archaeologists and historians believe that the girl was sacrificed to the gods.