India, Nov. 2 -- The South is filled with natural wonders, from dramatic gorges and massive cave systems to beautiful wetlands and pristine beaches. If you find yourself in East Tennessee, specifically, you'll be within driving distance of the incredible Great Smoky Mountains National Park, America's largest underground lake (The Lost Sea), and a waterfall known as Ruby Falls.

Ruby Falls isn't your ordinary waterfall. "The most notable difference is that the Ruby Falls waterfall is underground," says Hollie Baranick, the tours and guest experience manager at Ruby Falls. "There are not many other underground waterfalls that are so easily accessible to the public."

Located more than 1,000 feet beneath the surface of Lookout Mountain, the ...