Spring Mill State Park

Twin Caves - Donaldson Cave

Useful Information

Location: South of Bloomington. SR 37 south 59 km, at Mitchell turn east on SR 60, on the north side of the highway.
Open: Park: all year daily 7-23.
Twin Cave: Memorial Day to Labor Day daily 9-16:30.
Donaldson Cave: all year.
Fee: Gate fee: Indiana car USD 4, Other car USD 5, Pedestrian USD 1.
Twin Cave: Adults USD 3, Children (0-12) USD 1.
Donaldson Cave: free.
Classification: SpeleologyKarst cave
Light: bring torches
Guided tours: Twin Cave: L=152 m, D=20 min.
Bibliography: C.B. Rexroad, L.M. Gray (1979): Geologic Story of Spring Mill State Park, SPG7, Illus. USD 0.10
Address: Spring Mill State Park, Box 376, 3333 State Rd. 600 East, Mitchell, IN 47446, Tel: +1-812-849-4081 and +1-812-849-4129 (cave).
As far as we know this information was accurate when it was published (see years in brackets), but may have changed since then.
Please check rates and details directly with the companies in question if you need more recent info.


1832 village and mill purchased by the Hamer brothers and renamed Spring Mill.
1865 some forest purchased by George Donaldson.
1930s repairs and reconstruction by the Civilian Corservation Corps (CCC).
1972 Donaldson Woods designated a National Natural Landmark.


Spring Mill State Park has two caves open to the public. Both are exceptional. While Twin Cave is almost a show cave, it is done completely by boat. The boat follows the subterranean stream 150 m into the cave until it turns around. During heavy rain periods the caves may be too flooded to offer tours.

Donaldson Cave is the second cave in the park, visited during so-called nature walks. It is an easy horizontal cave, all equipment the participants need is a torch. The cave is home to the endangered species of the northern blind cave fish. Donaldson Cave is named after George Donaldson, who came from Scotland and purchased a tract of forest in 1865. He did not allow cutting of timber or hunting. Thanks to his efforts the 27 ha Donaldson Woods Nature Preserve today has native trees over 300 years old. This is a rare virgin hardwood forest similar to that which once blanketed most of Indiana.

The cave system is only one one sight of a 535 ha park, which includes many karst features such as sinkholes and stream risings. Mitchell Karst Plain is a nature preserve with one of the highest concentrations of sinkholes in the United States, in average 40 per square kilometre. Central to the park is the restored pioneer village complete with working grist mill powered by water from one of the caves. The 19th century grist mill ran day and night in its heyday, as farmers waited up to ten days to grind their corn and wheat into meal.