7 Hidden Natural Wonders in the United States - Page 3 of 9

Lost River Cave, Kentucky

You’ve probably heard of Mammoth Cave National Park, the largest underground cave system in the world, but what about Lost River Cave, also in Kentucky? An underground river in Bowling Green, the Lost River Caves are a natural wonder with intriguing history: The caves are where fugitive Jesse James hid out on his run from the law, and are believed to have also functioned as shelter to Native American tribes. Explore the cave by boat or book a zipline tour through the surrounding wilderness.