Spring Mill State Park

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Spring Mill State Park is a 1,358-acre (5 km2) state park located on the Mitchell Karst Plain, which allowed caves and sinkholes to form in the limestone. Caves include Bronson Cave, Twin Caves, Shawnee Cave (Donaldson Cave), and Hamer Cave.

A portion of the park is virgin timber, protected in the Donaldson Woods Nature Preserve.

The Mitchell Karst Plain Nature Preserve is notable for its large number of sinkholes, more than 1000 per square mile.

Many of the park's features were constructed by the Civilian Conservation Corps in the 1930s, including the Spring Mill Inn, Spring Mill Lake, and most of the trails.

A settler village can also be found in a valley in the park, featuring a historic watermill and nineteen other structures. A stream runs through the village, which is fed by a spring in Hamer Cave and powers the watermill.