Bonne Terre Mine
This mine operated for a century before it closed down in 1962. The groundwater was held at bay with the use of pumps but when the mine shut down the pumps also were turned off. Thus 88 miles of subterranean passages quickly flooded with groundwater creating the Billion Gallon Lake. Now a popular tourist destination for an underground boat ride, scuba divers also frequent here to swim through the crystal clear waters and look for artifacts from a bygone mining era.