At more than 144 miles in length, the cave at Jewel Cave National Monument is the second longest in the world. Also in South Dakota, you will find Wind Cave National Park where the fourth longest is located. At least, those are the current statistics, which keep changing as caves around the world are continually explored and found to be longer. Some of these statistics are debatable, but what is clear is that a number of the world's most extensive caves are in the United States. Mammoth Cave in Kentucky, at more than 365 miles in explored length, consistently places as the longest. South Dakota caves are some of the most amazing attractions in the state.
The caves in South Dakota are primarily of limestone, and all of them (the known ones, at least) are located in the Black Hills in the southwestern part of the state. Many of them are sacred to the Native American people of the region. The Jewel Cave National Monument is located on Mount Rushmore Road (Route 16) just west of the town of Custer and Custer State Park. The first written history of the cave is from 1900, when miner brothers filed a claim, entered, and discovered crawlways and rooms with low ceilings coated with beautiful calcite crystals that sparkled like "jewels" in their lantern light.
In 1928, the Jewel Cave Corporation was formed and provided tours to the public. Park rangers from Wind Cave National Park arrived in 1933, and began improving and administering the site. But the cave was small, and many wondered if other, more important, South Dakota caves made this one invalid as a tourist attraction. Significant exploration in the late 1950s and early 1960s extended its length to more than fifteen miles. Today, this is one of the most important caves in South Dakota and attracts hundreds of thousands of visitors.
In addition to the cave tours, there are other things to do on the surface of Jewel Cave National Monument including exploring the ponderosa pine forest and rugged canyons in the 1,279-acre park, admiring the 339 species of beautiful colorful wildflowers and viewing the more than 129 species of bird life. There are also self-guided hiking tours on several trails. Nearby attractions include the iconic Mount Rushmore (less than 35 miles away), Devil's Tower, and Custer State Park.
There are other caves in South Dakota in the Black Hills. Of all the caves in the United States, none contain the vast variety of formations found in the Black Hills. They have more unusual box work than any other caves in the world. Box work is usually composed of thin calcite blades that project from the walls and ceilings, creating a honeycomb or box-like formation. Eight total Black Hills South Dakota caves are open to the public, providing some of the largest concentrations of passageways in the world. Mount Rushmore Cave, featured in the film National Treasure II, boasts an incredible number of stalactites and stalagmites. Bethlehem Cave, Sitting Bull Crystal Caverns, and the Black Hills Caverns are located near Rapid City.