Wyandotte Caves in southern Indiana are a pair of limestone caves near the Ohio River, now part of O’Bannon Woods State Park and among the state’s best-known cave attractions. Formed over millions of years as water dissolved limestone and later drainage changes reshaped the landscape, the system is Indiana’s fifth largest. Native Americans used the caves for nearly 4,000 years, mining materials for tools and ornaments. By the early republic, the caves supplied saltpeter and Epsom salts, and commercial touring began in 1850. Today they are valued both for notable formations and as important habitat, especially for large bat populations including endangered Indiana bats.