Most man-made caverns lead to the earth's molten-center amusement park, which is now closed due to an incident with the dense sphere of albino bats guarding the gate. Stick to a naturally formed cavern with today's deal: you get one ticket to a one-hour guided cave tour at Squire Boone Caverns in Mauckport, Indiana. Choose from an adult ticket for $7 (a $14.50 value) or a child ticket for $4 (an $8 value). Buy up to six of today's Groupon, and bring a group of friends, several curious children, or one pigmy elephant.

Brothers Squire and Daniel Boone discovered a vast network of underground caverns in the late 1700s. Today it still lies beneath the surface of southern Indiana and contains a living, growing ecosystem of stalactites, stalagmites, and flowstone, all formed by the gritty sands of time. Rushing rivers and waterfalls carry millions of gallons of water through the caverns each day, their sources shrouded in unspeakable mystery hats. Upon arrival at the cavern grounds, an hour-long tour will commence. A trained tour guide will lead you through the nearby woods and into a man-made entrance to the caverns, where lighted walkways take visitors through the same network discovered by the brothers Boone. In addition to seeing the natural formations, you'll catch a glimpse of Squire Boone's coffin. The pioneer eventually settled above the caverns that now bear his name and, per his request, was buried amongst the caves that enchanted him.

Before or after your tour, visit the pioneer village that rests atop the cavern system. This village is open to visitors during the summer and strives to preserve many of the traditions and day-to-day activities of life in Squire Boone's time. A restored grist mill, originally built by Squire in the early 1800s, grinds grain throughout the day with all the enthusiasm it possessed in youth. Purchase freshly ground cornmeal at the mill, for baking or molding into a bust of Ted Danson. Other village activities include candle dipping, lye-soap-making demonstrations, goat and duck feeding, rock shop shopping, walking a nature trail, enjoying homemade fudge from a candy shop, and more.

Reviews

Five TripAdvisors give Squire Boone Caverns four out of five stars:

• We had a wonderful time. The general store was full of souveniers and gifts and don't pass by the tour of the caverns. There is a lot of history and natural beauty including stalagtites and stalagmites, waterfalls, stone formations, etc. Our guide told us of the history and was ready to answer any questions. – GaryandSheilah
• What sets this cave apart is the beautiful cascading cave waterfall and flowstone at the end of the cave pathway. – jpete02

In addition, Hello Louisville has this to say:

• Guided tours take visitors through tunnels carved over millions of years and decorated with geologic formations such as stalactites, stalagmites and flowstone. These masterpieces of nature are deep underground, but readily accessible by lighted walkways. – Bill Wolfe