Jewel Cave National Park is one of the crown jewels of South Dakota. The third longest cave in the world, only about five percent of this immense place has been explored. You can take a tour during your visit, but there's one tour that only a small percentage of visitors take. Those brave souls get to see a part of the cave that most will never see.

Jewel Cave offers several tours to the public.

The Discovery Talk is a short, 20 minute tour where visitors enter one large room of the cave. It's suitable for almost anyone. The longer Scenic Tour requires visitors to traverse 723 stairs, and lasts 1 hour and 20 minutes. It's suitable for moderately fit guests and older children. The Historic Lantern Tour is a favorite for guests. It's rather strenuous and is only for visitors ages six and older who can bend, stoop and climb steep wooden stairs.

The most difficult tour at Jewel Cave is the Wild Caving Tour, and most visitors won't even attempt it.

To even be eligible to take the Wild Caving Tour, you first must wriggle through this cement block, which measures just 8.5 inches high and 24 inches wide.

Why does the park make you navigate this tiny tunnel? Because you're about to spend a lot of time doing just that...inside the cave.

The Wild Caving Tour takes three to four hours to complete. You must be at least 16 years old, and advanced reservations are required.

Make your reservation up to 28 days in advance. Call (605) 673-8300 for more information.

This tour is considered extremely strenuous.

You must be able to crawl on your belly through tiny tunnels, climb vertical sections using a rope, and scramble over obstacles.

You'll wear a hardhat with a headlamp, which you'll need...because this part of the cave is very, very dark.

You'll also need to bring special clothing: sturdy boots with rubber soles that lace up, long pants, a long-sleeved shirt, elbow and knee pads and a bag to put it all in after the tour. You'll also want to bring along a change of clothes for after the tour. The cave is full of black manganese deposits, which will stain your clothes. The park will provide you with the hardhat and headlamp.

If you're up for the challenge, the Wild Caving Tour is an adventure you'll never forget. You'll see rare hydromagnesite balloons, along with other formations only found in this portion of the cave.

The Wild Caving Tour isn't offered year-round, but the park does have some select dates available during the off season. Click here for tour dates and scheduling.

Check out this short video to learn more about the Wild Caving Tour:

Have you ever taken the Wild Caving Tour at Jewel Cave? We'd love to hear about your experience!