Spring Mill State Park in Mitchell, Ind. offers everything a state park should – nature, history, and culture. There's so much going on at this park, I had to make two episodes! In Part 1, you'll learn why old growth forests are important, find out what's hiding in the dark cave systems, and discover how you can explore the caves by foot or by boat.
My first visit to Spring Mill was on a 40-degree day in late December, and I immediately fell in love with the park. Even though the leaves were off the trees, the area was lush and green in the Pioneer Village and along the flowing creeks. The sound of the water flowing was peaceful, and the stone bridges were charming. I had the place mostly to myself and enjoyed discovering its beauty. There's something about going to a park on your own and exploring it without feeling rushed. The place opens up to you, and you feel like it's your very own.
I visited again in late August when the park was full of families picnicking, hiking, and exploring the caves. The grist mill was operating, the water wheel turning, and the energy in the park was high. I loved the park’s active days just as much as the quiet ones!
IN the Podcast Episode
In the first of two episodes about Spring Mill State Park, I cover the natural resources and park’s history. You’ll learn about Donaldson’s Woods and the park’s virgin forests. Then we’ll visit the caves and find out which ones you can explore! We also discuss an unusual bird that showed up in 2025, the brown booby. Finally, you’ll hear about all the updates to the recently renovated inn and nature center.
Listen to Spring Mill State Park, Part 1: Cave Adventures and Ancient Forests on Apple or Spotify.
Park Features
Spring Mill State Park is home to a wide representation of natural features. Donaldson’s Woods is one of the most important segments of original forest in the state of Indiana, and the cave system visitors can access by hiking and boating is incredible as well. There are three nature preserves in the park, the Pioneer Village and grist mill, a long history with the Civilian Conservation Corps, and the Gus Grissom Memorial with a history of space travel. You’ll also find the traditional state park features like campgrounds, a nature center, a small lake for fishing and boating, and hiking trails. Spring Mill is a beautifully complex park with much to learn about nature and culture! With so much to cover, we’ll focus today on the natural resources. Next week, you’ll learn about the grist mill and the Grissom Memorial.
The Old Growth Forest of Donaldson’s Woods
While every state park is full of trees, many of them were planted by the Civilian Conservation Corps in the 1940s. At Spring Mill State Park, the Donaldson’s Wood Nature Preserve is a unique place because of the age of the trees in it. To learn about the nature preserve, I spoke with Wade LaHue, the park’s interpretive naturalist.
Ever since he was a kid, Wade has loved the old-growth forests in Donaldson’s Woods, named for George Donaldson from Scotland. Wade told me the history of the man who once owned part of the park. Donaldson’s wife and father both died soon after he was married, leaving him with a large family fortune. Donaldson was imprisoned in Scotland for political activities that ran against the government. He eventually escaped and made his way to America in the 1830s, purchasing and preserving land in various places, including 181 acres east of Mitchell, Ind.
Donaldson was apparently a very eccentric guy. The rumor was that hummingbirds responded to his call, and he would hand-feed them from a shell. He was also extreme in protecting his land. Wade shared a story about Donaldson, “He wouldn't even let a lash be drawn, you know, like a carriage lash, be drawn out of the wood there. He was very protective of that space and hunting as well.” Donaldson wanted the land as nature desired it, so he kept everyone off it. The long-term impact is impressive because it means there are trees at Spring Mill that are over 300 years old!
Today, Donaldson’s Woods is a 145-acre nature preserve with 67 acres of original, old-growth forest in Indiana. Wade said, “It’s mesic forest, which means it's got beech and maple and oak trees and hickory trees and lots of tulip poplar trees, our state tree.”
I love trees and hiking through them, but I wasn't sure what differentiated an old-growth from a young forest. Wade explained, “The understory of the forest is more shaded. It provides cooler habitats for different types of plants that don't grow in other younger forests. Older trees provide a stronger bulwark against things like wind and weather damage, so those communities are more well protected with those larger trees in there to stabilize them… Big trees, when they succumb to time and disease or whatever, that six-foot diameter shaft of tree hollows out and becomes home for gray fox or raccoons and possums and flying squirrels, things like that, that are exciting to get to have and to see. The younger forests don't provide as good a cover and as good a habitat for them.”
A great way to see the old-growth forest is by hiking Trail 3 through Donaldson’s Woods Nature Preserve. It's 2.5 miles long, and while the map called it rugged, I might classify it as moderate to rugged. That trail will also take you past three of the four caves on the property, and that's where we're headed next, as long as you aren’t afraid of the dark!
Exploring the Cave System
Another person I got to interview is Mark Young, the park manager. Mark has worked for Indiana State Parks for over 50 years, and he told me about the impressive cave system that is one of Spring Mill's most popular features. He explained that every entrance or cave opening is given a name, even if they’re part of the same system. At Spring Mill, Donaldson Cave, Bronson Cave, and Twin Caves are part of the same system, and people can go in them by boat or by foot.
Additionally, there is one other cave in the Pioneer Village. Hamer Cave is within the park boundaries, and some of the water from it powers the grist mill and flows through the village. However, a local concrete company owns the water rights, and the cave is not accessible to the public.
Thankfully, the three main caves are fun enough to explore. Mark shared, “Over the years, we've developed specific use policies. You can take cave boat tours up into Upper Twin Caves. However, if you are part of a group of at least three people, and you feel like you're willing to do something a little exciting, you can go from Bronson Cave to Donaldson Cave.” Hiking from Bronson to Donaldson Cave does require a permit from the park as well as a lot of nerve. Mark said the hike is more than simply walking through the dark, “You're in the stream a lot of the ways through there. There's one spot, generally, you're going to have to swim, so it is cold, you have to be prepared for it… We recommend that you have appropriate caving gear. That would include a helmet, proper boots or shoes for slippery conditions, and then some type of light.” Depending how high the water is, this could be quite the adventure!
If you want a cave tour without swimming in water, you can take a boat ride through Twin Caves. Wade, the park’s interpretive naturalist, said paying for this tour is worth it because “We have staff that gives a tour, and talks about the formations and everything that's in there. Twin Caves is totally wet, it's totally flooded, so you can't otherwise access that cave.” Boat tours for Twin Caves are open from Memorial Day to Labor Day, and sign-ups (which are weather dependent) happen each morning until the tours are full.
The boat tours are for ages 3 and up, and riders will have to wear a life jacket. The custom-made boats are made for the narrow cave, and they hold about eight people. On the tours, the guide carries a light, and they're able to use their flashlight to help people spot blind cave fish or cave salamanders.
There is one more option to experience the caves – hiking into the dry side of Donaldson Cave. There’s an easy, fairly accessible path with a smooth ramp to the mouth of the cave. You can still experience total darkness or bring a flashlight to explore the sizable cave. It goes about 150 feet deep, and you do not need a permit to check this side out. On my own, my cell phone flashlight did nothing to pierce the darkness. But when I visited Spring Mill in August, there were probably dozens of people in the cave, and our collective flashlights made it easy to look around. I was shocked at how big the space was! It kept kids and adults entertained for quite a while and made this park a favorite with my niece and nephew.
Support from the Friends Volunteer Group
Spring Mill State Park has been loved for a long time. Their Friends group is active and invested in supporting the staff’s projects and ideas. They have been able to contribute to major purchases and small yet practical needs that go beyond the park's budget. I talked with member Teena Ligman about their work. She told me the Friends group paid for new docks for the boat launch, a leaf blower, and colorblind binoculars at the lake. They help with craft fairs and holiday events to raise money for these projects. You can learn more about The Friends of Spring Mill State Park on their website and become a member too.
The staff also told me, “We have groups that have been coming here…for 70 years, generations and generations of people that have used the same building and come here every year… It's such an intrinsic part of the community. It's just a staple and a foundation of the county in a way that defines this property.” This beautiful, historic place is beloved for a reason.
Planning Your Visit
I enjoyed visiting Spring Mill in both December and August. The great thing about the caves is that they’re consistently around 55 degrees year-round. In the winter, they feel warmer than you’d expect; in the summer, they’re wonderfully cool! The flowing creek is a fun spot for kids to play in the summer, while the lush green grass and bubbling water are beautiful and transportive even in the winter.
I’m not sure there’s a bad time to visit! I’m looking forward to another trip down when I can take the Twin Caves boat tour. Hopefully, you can get there this year too.
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