This Underrated US State Park Is Known For Its Enticing Underground Caves

Adventurers who are passionate about the great outdoors and who long to explore new places will find that U.S. state parks offer a variety of unexpected thrills. When you make time to add a state park to your itinerary, you'll find yourself in good company. According to the National Association of State Park Directors, America's state parks enjoyed more than 867 million visits across locations in all 50 states. If you happen to be a traveler looking for unique outdoor activities that take you both above and below ground, you won't want to miss a chance to visit Spring Mill State Park.

Located in Mitchell, Indiana, Spring Mill State Park sprawls across an impressive 1,400 acres of scenic terrain. The park invites visitors to come and hike, picnic, bike, or even paddle their way through a day on Spring Mill Lake alongside family and friends. Rich in history, the park is home to a restored Pioneer Village dating back to 1814. There's also an interactive visitor center where guests can learn about local flora and fauna that have long defined the landscape. But for all of the above-ground beauty you're sure to encounter, Spring Mill State Park is perhaps best known for its maze of underground caves just waiting to be discovered.

The collection of underground caves found throughout Spring Mill State Park creates fascinating opportunities for visitors looking for one-of-a-kind adventures. While each cave provides a different experience for guests, the majority are interconnected by miles of waterways that flow beneath the park's rich terrain. Interestingly, the waters that flow through the cave system never freeze, as the caves maintain a year-round temperature of around 54 degrees Fahrenheit. Wildlife enthusiasts will love that the caves at Spring Mill State Park also provide a perfect home for the endangered Hoosier cavefish, a species of fish that's entirely blind and ultimately thrives within the dark and protected waterways of the subterranean caves.

Some of the most accessible caves to explore, as part of a guided tour or registered exploration group, include Bronson, Donaldson, Hamer, Hidden, and Twin Caves. Guests looking to explore Bronson Cave or the wet side of Donaldson Cave may do so year-round, as long as they've registered as a tour group. Upper Twin Cave is open to registered guests exclusively between November 1 and May 15. At specific times throughout the year, visitors can register for a place on a naturalist-guided tour of Endless Cave and River Cave. If you want to tour individually, you're free to explore the dry side of Donaldson Cave all year long.

A great way to tour Twin Caves while you're visiting Spring Mill State Park is by booking a spot on one of the summertime boat tours. This 20-minute excursion is led by a guide who pulls the tour boat through the stream 500 feet into the cave, so guests can enjoy more leisurely sightseeing opportunities. Along the way, your guide will point out wildlife like fish and bats that inhabit the cave, as well as unique rock formations to admire. It's good to note that boat tours run every 30 minutes and can be booked exclusively with a same-day reservation made at the Twin Caves Shack. The tours are weather-dependent, so it's always advisable to check the weather forecast ahead of time.

If you're looking for more rugged caving opportunities, take a short detour to the nearby Cave River Valley Natural Area. A partnership between Spring Mill State Park and the Indiana Karst Conservancy allows registered groups to enjoy a self-guided spelunking expedition of these caves, as long as they agree to complete online training ahead of time. The training covers vital decontamination procedures to adhere to while caving, to prevent the spread of lethal diseases to the cave's essential bat populations.