The park's grist mill was constructed in 1817 and uses a wooden undershot waterwheel to power its grinding stones.
The subterranean Twin Caves system is home to the endangered Northern Cavefish, a species that is completely blind and lacks pigment.
The park's limestone geology creates a massive 'karst' window, where the underground river emerges and then disappears back into the earth.
Astronaut Gus Grissom’s original Gemini 3 space capsule, the 'Molly Brown,' is preserved and displayed in the park's memorial center.
The Pioneer Village was historically a bustling industrial hub that utilized the constant flow of spring water to power multiple mills simultaneously.
The park contains remnants of virgin forest that were never cleared by early settlers, providing a rare glimpse into Indiana's original landscape.
Spring Mill State Park is a 1,358-acre Indiana state property centered around a restored 1817 pioneer village and a sophisticated karst landscape. The site is anchored by a three-story limestone grist mill, which remains functional and continues to grind corn using water power. Beneath the surface, the park features the Twin Caves, a subterranean river system accessible via guided boat tours. The Pioneer Village includes twenty historic buildings, such as a distillery, apothecary, and cobbler shop, showcasing early 19th-century industrial life. The park grounds also house the Gus Grissom Memorial, dedicated to the Mitchell-born NASA astronaut who became the second American in space. Diverse ecosystems within the park include virgin timber stands and sinkhole plains characteristic of south-central Indiana. Visitors can access the Spring Mill Inn for overnight lodging located directly within the park boundaries. The park provides extensive hiking trails that traverse hilly terrain, forest canopies, and cave entrances.
The wooden waterwheel at the Grist Mill during the early morning hours.
Book your cave boat tour immediately upon arrival at the park gate, as tickets often sell out early in the day.
Wear sturdy, closed-toe walking shoes to navigate the limestone paths and uneven ground near the caves.
Bring a light jacket, as the cave environment maintains a significantly lower temperature than the surface regardless of the season.
Do not attempt to enter the caves outside of authorized boat tours, as the water levels can rise rapidly due to rainfall.
Cave boat tours are seasonal and typically operate from late spring through early autumn; tours are subject to cancellation based on water levels.
Maintain a quiet volume near the caves to avoid disturbing the sensitive ecosystem; pack out all trash.
