So much of our travel is on the road or in the air…but what if there was a really cool experience underground? There is a world of exploration in underground caves.

You don’t have to be a professional spelunker to do it, and there are probably some opportunities in your own backyard.

Wind Cave National Park in South Dakota’s Black Hills is the first cave network to be designated a national park.

The terrain here is totally unique. The walls are filled with boxwork patterns, which are made of calcite strands that create a box-like, or honeycomb pattern.

In Kentucky, Mammoth Cave is probably the longest known cave system in the world, where at least 400 miles have been explored and mapped.

If you’re looking for something really intense, they even have a tour that basically involves army crawling through the tunnels on your stomach.

Believe it or not, you can actually sleep in a cave. Beckham Cave Lodge in Eureka Springs, Arkansas, which is reopening early next year, is built right into the Ozarks. You can explore other parts of the cave straight from your room.

For more information, visit the National Parks Archives.

Keep reading for more travel tips.