Spring Mill State Park

Spring Mill State Park is a 1,358-acre (5 km2) state park in the state of Indiana. The park is located to the south of Bloomington, about 3 miles (5 km) east of the town of Mitchell on Indiana Highway 60.

The park is located on the Mitchell Karst Plain, which allowed the park's caves and sinkholes to form in the limestone. The caves include Bronson Cave, Twin Caves, Shawnee Cave (Donaldson Cave), Hamer Cave, and others. A boat tour of Twin Caves is run by the Indiana Department of Natural Resources, which travels about 500 feet (150 m) into the 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. Heritage interpreters demonstrate crafts and skills from the 1860s. The Hamer Cemetery is located south of the village. The area, 295 acres (1.19 km2) total, was purchased for the state park from a cement company for a single dollar. Steam power allowed watermills to be erected anywhere. Restoration of the village was spearheaded by Richard Lieber and E.Y. Guernsey (employed by Indiana's Department of Conservation) in the late 1920s and early 1930s.

Also of interest is a memorial to native resident of Mitchell, Gus Grissom, one of the original Mercury Seven astronauts, who died in the Apollo 1 accident. The memorial features the spacecraft from Grissom's Gemini 3 space flight, nicknamed by Grissom the "Molly Brown" (after the play The Unsinkable Molly Brown), as well as a short video about the life of Grissom, and artifacts such as a space suit, helmet, and many personal effects.

A Nature Center is open from spring through fall and features live snakes, a bird-watching window, natural history displays, and a children's area. During the winter, a small Nature Nook is available instead at the Spring Mill Inn.

The campground features 188 Class A campsites which include 30 amp electric service, a fire ring, and a picnic table for each site. Thirty-five primitive campsites and youth camping are also available. Four "comfort stations" are located in the campground, which include modern plumbing, restrooms and showers. A camp store is accessible from both inside and outside the campground.

The park was the subject of a Rescue 911 segment that aired on October 17, 1989 about a man that became trapped and was later rescued in Donaldson Cave.