Actun Tunichil Muknal is a cave in Belize, near San Ignacio Cayo, notable as a Maya archaeological site that includes skeletons, ceramics, and stoneware. The most famous of the human remains is known as "The Crystal Maiden", the skeleton of a teenage girl, probably a sacrifice victim, whose bones which have been completely calcified by the natural processes of the cave, leaving them with a sparkling crystallized appearance. There are several areas of skeletal remains in the main chamber.
The ceramics at the site are significant partially because they are marked with "kill holes", which indicates they were used for ceremonial purposes. Many of the Mayan artifacts and remains are completely calcified to the cave floor. The Mayans also modified cave formations here, some to create altars for the offerings, others creating silhouettes of faces and animals, some projecting a shadow image in the cave. The cave is extensively decorated with cave formations in the upper passages.
Animal life in the cave includes a large population of bats, large fresh water crabs, crayfish, catfish and tropical fish. Large invertebrates and various predatory spiders also inhabit the cave. Agouti and otters may also use the cave. These and many other species are quite common in river caves of this size in Belize.
The Belize Tourism Board has granted licenses to a small group of agents to conduct tours to this cave, in an attempt to balance its protection against tourist revenue.
The cave is located in the Tapir Mountain Nature Reserve. The main cave system in about 3 miles long. It consists of a long river passage for approximately two miles, ending at an upstream sump. A series of upper prehistoric passages continues another mile past the sump through massive breakdown boulders and giant rooms. The cave can be exited through a tight squeeze ending in a giant sink hole collapse in the jungle. The cave's upper passage called "The Cathedral" is located about 1/3 of the way in from the lower entrance. Here 14 skeletal remains have been found, and numerous examples of ancient Maya pottery remain.
Information based on http://en.wikipedia.org/wiki/Actun_Tunichil_Muknal