Organ Cave located in southeast West Virginia, near White Sulfur Springs and Lewisburg, is one of the longest, best-known, and most significant caves in the United States. Its surveyed length of 60.5 km ranks it as the seventh longest cave in the US and the twenty-first longest in the world. At 148 m, it is also the fourth deepest cave in West Virginia. It is listed as a Natural National Landmark with published accounts of tourism dating back to 1837. Organ Cave is rich in biodiversity with twelve different cave-limited species, establishing it as a significant system.
Additional species found within the cave include mites, spiders, springtails, beetles, and bats.
The seven species of bats residing within Organ Cave include both the Indiana Bat, which has been placed on the U.S. Federally Endangered List, and the extremely rare Small Footed Bat. Logging and other highway construction preparations will increase runoff and are therefore causes of concern for the overall health of the system. Snail Shell Cave located just southwest of Murfreesboro, Tennessee, is the longest continuous cave in the central basin of Tennessee with 20 km of passages. It contains two underground streams and a large sinkhole opening with dimensions of 30 by 61 m. There are at least three endemic species to Snail Shell Cave including a cave beetle, cave snail, and an undescribed species of blind aquatic snail.