Illinois Caverns State Natural Area

Illinois Caverns is a cave system extending through about 6 miles of mapped passages beneath Monroe County. The passages feature mineral formations including stalactites, stalagmites, flowstone, and rimstone dams that developed in the limestone rock.

The cave was discovered in 1901 by Frederick Eckert and opened to visitors shortly after. Early tourists accessed the site by train and explored the passages using kerosene lamps.

The natural area maintains geological records of water erosion processes that shaped underground passages through limestone and dolomite bedrock over millions of years.

Visitors need sturdy boots, a hard hat, and at least three light sources to navigate safely in the dark passages. A permit must be obtained at the site office before entering.

The cave is home to the Illinois Cave Amphipod, a rare species found only in this location and a few neighboring cave systems. This blind aquatic creature has adapted to life in complete darkness.

Location: Illinois

Inception: 1985

GPS coordinates: 38.23556,-90.13694

Latest update: December 9, 2025 18:44