Explore One of Indiana’s Most Unusual Cave Trails

I have a confession: I didn't like entering underground places, and I know I am not alone in saying that. Going inside narrow openings always made me anxious. Several years ago, I conquered my fear when I toured an underground waterfall. Descending into the cave was like a trip to an enchanting prehistoric world full of untapped wonder. Ever since then, I don’t mind hiking through the subterranean world, and I’m always up for another adventure. Are you brave enough to discover what lies beneath the surface? Grab your boots and headlamp (if you have them), and let’s explore the Twin and Bronson Caves Trail inside Spring Mill State Park. This unforgettable cave hike in Indiana will inspire your wanderlust. And who knows, maybe you’ll overcome your fears, too.

My favorite thing about Spring Mill State Park is that it offers something for everyone to enjoy. There are historical sites, water recreation, hiking, camping, mountain biking, and more. But the park has a secret weapon for folks brave enough to live on the edge—the caves!

Multiple hiking trails lead to caves inside Spring Mill, but the Twin and Bronson Caves Trail is the most popular, and for good reason. Three caves (Twin, Bronson, and Donaldson) are accessible on the trek.

The two-mile loop trail has some elevation changes, and hikers will need to climb steps to see the caves. The good news is that there are no real obstacles along the way, as you trek through tree canopies and the karst terrain. The scenic area is quite pretty and known for caverns, sinkholes, and rocky formations caused by water erosion.

Within a short distance from the parking lot, you’ll get to the steps that lead to Twin Cave. Water pours from the cracks inside the rocks, so be sure to take time to soak up the sounds and the views. The cool part about this cave is that you can book a 20-minute boat tour (in person) with a guide to see the endangered blind cavefish and other underground dwellers. It is a unique experience that the entire family can enjoy. Since the tour is seasonal, running from late May to mid-July and only on weekends in the later months, you’ll need to plan for the ride.  

After your underground excursion, head back on the trail to view the second natural wonder. Unlike the first cave, you can’t enter Bronson Cave, but you can view it from a platform. A collapsed sinkhole created the massive opening, and I can’t help but wonder what creatures live inside the hidden crevices. (Yikes!)

I love hikes where I can hear flowing water all around me, and there is no shortage of that here. The same stream flows through the cave systems along this trail. On your way to the last stop, there will be a couple of street crossings, so please be extra careful and watch for oncoming traffic.

For the true adventurers, the Donaldson Cave will be the highlight of this hike. You can enter the cave without a guide and explore it at your own pace. The park installed a wooden pathway over the flowing stream for easy access. Keep in mind that there might be some wet spots inside the cave, so it’s a good idea to wear waterproof shoes. I’d also advise that you bring a headlamp or flashlight. The inside of the cave can get dark, and the light from your phone won’t help when navigating.   

Carve out about two hours for this hike, but if you have the kids and a dog (on a leash, of course), you will likely spend extra time on this adventure. And if you plan to explore the interconnected trail system, you should have AllTrails+ on your phone to access the offline maps. It has come in handy so many times when I needed it the most.   

So, what do you think about this cave hike in Indiana? Are you brave enough for this below-ground adventure? Of course, you are! I promise that after this hike, Spring Mill will become your new favorite state park in Indiana. For more Hoosier State adventures, check out Only In Your State’s itinerary planner.