Ozark Underground Lab, Missouri

A privately owned cave developed to study cave environments and groundwater hydrology. Tours are led by flashlight, carefully avoiding stepping on any living organisms that might have wandered onto the dirt pathways, such as the blind salamanders that can be found in the cave. The cave entrance has a locked doorway and a set of wooden stairs descending through a dug, vertical shaft leading 50 feet down to the cave. A natural opening is not used for human access. Features on the floor of the cave, such as skeletal remains of animals, are marked with quarter dollars to catch people's attention. Lab and office buildings are on the surface, and a bunk house and camp site are available for groups studying at the cave. Owned and operated by Tom and Cathy Aley.