Most people think of visiting big cities, national parks, and beaches when they plan a U.S. trip. There’s hardly anyone who’s ...

Discovered in 1878, Luray Caverns has been drawing visitors for over a century—and it's easy to see why. Located just west of ...

But Jewel Cave, which was designated a national monument in 1908, has more than 180 miles of mapped and surveyed passageways, making it the third-longest cave system in the world. The cave ...

Sweetwater, Tenn.? When a 13-year-old boy discovered what is now the world’s second-largest underground lake, he had to crawl through a muddy hole deep inside a cave and throw balls of dirt into ...

Gypsum caves, while rare, are not unheard of, even in the United States. For example, South Dakota's dazzling Jewel Cave National Monument is rich in gypsum crystals. But Alabaster Caverns stands ...