Jewel Cave, South Dakota was discovered in the 1900. It was declared a National Monument in 1908 by President Theodore Roosevelt. These images are from our 2012 visit. Now, there is a tour where you can do some actual caving. However, you have to be able to fit through some tight spaces. While my then 4 year old daughter wouldn’t have had any problems, I wasn’t keen on attempting such a feat.
The tour that we embarked on consisted of taking an elevator down into the caves and walking on approved paths, stairs, etc. It’s still a bit of a hike though. According to the brochure, there are 723 stair steps in the Scenic Tour which we took. Also, if you visit during the summer like we did, it’s significantly cooler in the caves than it is outside, so come prepared.