Unthanks Cave Natural Area Preserve

Unthanks Cave Natural Area Preserve is a 171 acre Natural Area Preserve in Lee County, Virginia. It protects the entrance to Unthanks Cave, which houses significant biological diversity and a wide variety of invertebrate life. The cave's streams drain a significant karst area south of the Powell River.

A rare species of hydrobiid snail was first discovered in Unthanks Cave in 1986. Holsingeria unthanksensis, also known as the thankless ghostsnail, has since been found in additional cave streams in Lee County, with an additional population noted 500 km north in Skyline Caverns. Additional unusual species found within the cave include a second hydrobiid snail, the Powell Valley planarian (Sphalloplana consimilis), the Southwest Virginia cave isopod (Caecidotea recurvata), and a cave-dwelling carabid beetle.

The only known entrance to the 7 mi cave was purchased by The Nature Conservancy in 1987, and was the first cave system purchased in Virginia by the organization. The Nature Conservancy gave the property to the Virginia Department of Conservation and Recreation in 2004, although they continue to conduct research at the site.

Although previously popular with spelunkers due to the cave's large speleothems, Unthanks Cave is today gated and inaccessible except for official scientific monitoring and inquiry.