Blanchard Springs Caverns, in the Ozark–St. Francis National Forest of northern Arkansas, is an unusual tourist cave as the only one owned by the U.S. Forest Service and the only federally owned example outside the National Park System. Known locally by the 1930s and systematically explored from the 1950s, it opened to the public in 1973 and now offers guided routes through a three-level system. Geologically, it is one of Arkansas’s major caves, with 8.1 miles of surveyed passage, active calcite formation, and evidence of changing underground streams. Its Giant Flowstone ranks among the largest in the United States.