Jewel Cave passes 200 miles, one of the longest caves in the world
In the dark beneath the Black Hills, volunteers have measured their way past 200 miles of passage, and they are still going. This is how Jewel Cave became one of the longest caves on Earth.
Jewel Cave National Monument in the Black Hills of South Dakota is one of the longest caves on Earth. In December 2018 a team of volunteer cave explorers surveyed its 200th mile of passage. Mapping has continued ever since, and today more than 220 miles of Jewel Cave have been measured and recorded, which makes it the second longest cave in the United States and one of the five longest known caves anywhere in the world.
What the 200-mile milestone is
On December 15, 2018, six volunteer cavers went underground at Jewel Cave and surveyed 3,338.75 feet of new passage. When they added it to the running total, the cave crossed 200 miles of mapped passage for the first time, finishing at roughly 200.3 miles. It was the result of decades of patient, foot-by-foot survey work by volunteers, and it moved Jewel Cave into a very short list of the longest caves ever explored.
The 200-mile mark is a survey figure. It counts only passage that explorers have physically reached, measured, and drawn onto the official cave map. It is not an estimate of how big the cave actually is. By most accounts only a small fraction of Jewel Cave has been mapped so far, so the total will keep climbing as exploration continues.
Why 200 miles matters
Reaching 200 surveyed miles put Jewel Cave among the giants of the underground world. Since then, ongoing exploration has pushed the mapped length past 220 miles. That ranks Jewel Cave as the second longest cave in the United States, behind only Mammoth Cave in Kentucky, and among the five longest caves known worldwide.
Jewel Cave sits just a few miles from its neighbor, Wind Cave National Park, which is itself one of the longest and densest caves on the planet. Having two of the world's great caves within an hour's drive of each other, in the same corner of the Black Hills, is part of what makes this region special for cavers, scientists, and visitors alike.
How Jewel Cave is explored and mapped
Almost all of the exploration at Jewel Cave is done by volunteers. Skilled cavers, many of them members of local caving groups, spend long days underground pushing into new passage, then measuring and sketching every foot of it so it can be added to the official map. A single survey trip might add a few hundred or a few thousand feet, and there are still hundreds of unexplored side passages, called leads, waiting to be checked.
That is why the mapped length keeps growing. Each new mile represents real people crawling, climbing, and squeezing through the dark to reach ground no one has ever recorded before, then carefully documenting it. The 200-mile milestone, and every mile since, is a volunteer achievement.
The 200-Mile Celebration and Reunion
To mark the milestone, Jewel Cave National Monument, its nonprofit partner the Black Hills Parks and Forests Association, and local cave explorers held a 200-Mile Celebration and Reunion in Custer, South Dakota, over the weekend of June 28 to 30, 2019. The weekend brought together cavers, rangers, scientists, and the public for talks on cave exploration and science, exhibitions and demonstrations, youth activities, and special tours at the monument, including historic lantern tours.
The celebration is over now, but the story it honored is still being written underground with every new survey trip.
How to experience Jewel Cave
You do not have to be a cave explorer to see Jewel Cave. The monument offers ranger-guided tours for a range of abilities and interests, from an accessible Discovery Tour to the more active Scenic Tour, along with historic candlelight and lantern tours that show how the cave was explored in earlier days. Tours can sell out in the busy season, so it is worth planning ahead and checking the monument's tour schedule and reservation details before you go.
The visitor center, exhibits, and surface trails at Jewel Cave National Monument are open to everyone, and the surrounding Black Hills National Forest offers hiking and wildlife nearby.
Take home a piece of the milestone
To mark the 200-mile achievement, we carry the Jewel Cave 200 Mile Lantern Pin, a small collectible that nods to the historic lantern tours and to two centuries of mapped passage.
Jewel Cave, answered
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See one of the world's great caves
Plan a ranger-guided tour, walk the surface trails, and stand above 220 miles of mapped passage in the Black Hills of South Dakota.
