It was the last day of our South Dakota trip and we had one more thing on our itinerary – Jewel Cave National Monument. Fortunately, we booked tickets ahead of time and we’re glad we did. There were no tickets available for walk-up visitors.

Jewel Cave is home to the third largest cave system in the world and the second largest in the US behind Mammoth Cave National Park. Discovered in 1900 by mining prospectors, Jewel Cave became the first national monument to protect a cave in 1908. Until the 1950s, cavers only discovered two miles of passageways. Today, explorers have mapped 215 miles of trails and still haven’t found the end.