Caves are nature's scenic cellars, where rocky roofs protect bats from tornadoes and water nymphs store their old couches for the day their kids move out. Experience such subterranean stupendousness with today's Groupon: for $7, you get one ticket to Lost River Cave (up to a $15 value) in Bowling Green, Kentucky, located mere minutes from I-65 and about an hour from downtown Nashville. Your tour is split up into two parts—a 20-minute guided walking tour along the river's edge leading up to the cave and a 25-minute boat tour inside the cave, as well as free, self-guided tours of Lost River’s seasonal butterfly habitat and Blue Hole nature trails. Be sure to call ahead to check tour-date availability.

Dazzling formations and a remarkable register of past residents renders the Lost River Cave a tour treasure for families, history buffs, and geological geeks alike. The cave's titular river offers spectacular sights, the finest views of which emerge on the cave boat tour, the only underground cruise of its kind in the state ($3.50 for ages 1–3, $10.50 for ages 4–12, and $15 for 12 years old and up). As the daylight suddenly vanishes and things begin to glow in the dark, one of Lost River’s friendly, funny guides will fill you in on the Lost River's prehistoric Native American roots, as well as its later habitation by Civil War soldiers and outlaws like Jesse James—painting a vivid picture of the cave's hospitable environs and its 8,000-year-old bellhop. Upon disembarking, you'll continue your sabbatical from sunshine with a further 20-minute guided walking tour of the cave. Visitors have been known to spot native pipistrelle bats, cave salamanders, eyeless crawfish, and skinny-dipping gnomes.

Once you escape the balrog and emerge back into the fresh air and sunshine, you can continue your hike around the 68-acre park's nature trails. Birdwatchers will want to bring binoculars to the Blue Hole Trails, where more than 130 different avian species make their roost and throw their keggers. Lepidopterists, meanwhile, can don a cocoon-shaped disguise and attempt to blend in among the fluttering works of art in the Lost River Cave's seasonal butterfly habitat.

Ever since a non-profit coalition formed to save the cave from years of dumping and abuse, Lost River Cave has developed into a safe, clean, and educational bastion of the Nashville area. All revenue generated from ticket sales goes toward preservation and development of the cave, with only a small portion of it going to the troll. Buy gift Groupons for any unusually pale friends and use their skin as illumination while wandering the wonders of Lost River Cave.

Reviews

TripAdvisors give Lost River Cave four stars and also make it the number two attraction in Bowling Green. Four Insider Pagers agree and give it four stars as well:

• Great place to take the family. The guides are intelligent, well informed and very witty. They made it a pleasure to take tour. The cave is steeped in history and very beautiful to tour. – 2glib72, TripAdvisor
• The cave was beautiful and the boat ride was exciting, safe and quiet. We loved the pipistrelle bats. – Oliveseeker, TripAdvisor
• Truly a gem in the heart of bowling green not far from major shopping and lodging off of i65! A place once forgotten turned into a dedicated educational nature preserve. Not only for nature but for history from prehistoric native American hunters, early settlers, Civil war, Night club tourist attraction to a forgotten past to today's race to save an amazing cave! – gary m., Insider Pages