The Niaux cave is part of an 8 miles (13 km) underground complex of which only 0.5 miles (800 m) are accessible to the public. The other part, the Clastres network, is only accessible by diving to professionals and shelters more than 500 human footprints as well as five animal representations, three bison, a horse, and a weasel. The latter is a unique representation of this animal in prehistoric parietal art.