Jewel Cave National Monument

Jewel Cave National Monument, in the southern Black Hills of South Dakota, protects the third-longest known cave in the world — a labyrinth of more than 220 mapped miles of passages, named for the sparkling calcite crystals (‘jewels’) that line its walls and ceilings. Beyond its namesake crystals, the cave holds an extraordinary variety of rare and delicate formations including neon-green hydromagnesite ‘balloons,’ moonmilk, frostwork and cave popcorn.

Located about 13 miles west of Custer, the cave is still being explored, and new passages are mapped each year. Wind rushes through its natural entrance as pressure changes, drawing explorers since it was first discovered in 1900. Ranger-guided tours range from easy scenic walks to adventurous, crawling wild-cave expeditions. Jewel Cave is among the most extraordinary cave systems in the world, a sparkling underground wonder and a treasured natural icon of South Dakota.

Jewel Cave is explored only by ranger-guided tours — the paved Scenic Tour passes the famous calcite crystal ‘jewels’ and main formations with easy walking; the more strenuous Historic Tour uses oil lanterns and explores older passages; and the challenging Wild Cave Tour (for those in good physical shape) involves crawling and squeezing through undeveloped passages. Above ground, a short hiking trail leads through ponderosa-pine forest near the entrance. Touring the cave — marveling at the crystals, the balloons and the rare formations — is the singular draw. Jewel Cave is an underground wonder unlike anything on the surface.

The cave is a constant 49°F year-round and tours run in all seasons (most frequently in summer, when advance reservations are strongly recommended). Above ground, late spring through fall is pleasant for the drive and the forest walk. Summer gives the most tour options, but shoulder seasons offer shorter waits. The cave tours are the draw in any season — book ahead in summer and always bring a jacket for the constant cave chill, regardless of the season outside.

Jewel Cave was discovered in 1900 when two brothers felt wind rushing from a small opening, followed the breath of the cave inside and found the sparkling calcite crystals. For decades it was known as a modest cave with only a few miles mapped; systematic exploration beginning in the 1950s has revealed it as the third-longest cave in the world, with new passages still being found. It was declared a national monument in 1908. Jewel Cave National Monument preserves this extraordinary crystal-lined labyrinth, a treasured icon of South Dakota and one of the great cave systems of the world.

Jewel Cave formed in the limestone of the southern Black Hills — groundwater dissolved the rock into a dense, complex three-dimensional maze of passages. The signature calcite crystals (‘jewels’) formed as mineral-rich water precipitated sparkling calcite on nearly every surface. The rare hydromagnesite balloons — hollow, paper-thin spheres of mineral that glow neon green under UV light — and the frostwork, moonmilk and cave popcorn all formed through distinct mineral-precipitation processes in the cave’s slowly evolving microclimate. The limestone, the groundwater chemistry and the cave’s long history of mineral deposition created this extraordinary crystal-lined cave.

Jewel Cave is home to several bat species, which hibernate in the cave’s passages in winter and are sensitive to disturbance and to white-nose syndrome, a devastating fungal disease. The ponderosa-pine forest above holds mule and white-tailed deer, porcupines, wild turkeys and various birds, with the surrounding southern Black Hills rich in wildlife. The cave’s bats and its rare cave organisms are sensitive. Visitors help protect the bats by following white-nose-syndrome screening procedures and avoiding cave entry outside of guided tours.

Jewel Cave harbors a rare subterranean ecosystem — cave-adapted organisms, specialized invertebrates and sensitive bat populations depending on the cave’s stable environment — alongside the ponderosa-pine and limestone ecosystem above. White-nose syndrome threatens the cave’s bat populations, and the cave’s microclimate and formations are sensitive to human disturbance. The aboveground forest and soils are also managed within the national monument. Protecting the cave’s formations, bats and microclimate, and the forest above, sustains both the ecology and the extraordinary beauty of Jewel Cave.

Jewel Cave National Monument holds a treasured place among the icons of South Dakota — the third-longest known cave in the world, a sparkling crystal-lined labyrinth of more than 220 mapped miles still being explored, home to rare formations found few places on Earth. Its underground beauty and ongoing scientific exploration embody the spirit of discovery. Jewel Cave is a cherished natural and scientific icon of South Dakota and one of the great cave systems of the world.

Jewel Cave National Monument is in the southern Black Hills of South Dakota, about 13 miles west of Custer on U.S. 16, and about an hour from Rapid City. An entrance fee is charged for tours. Tours depart from the visitor center and must be reserved in advance (especially in summer). The cave is a constant 49°F — bring a jacket. Some tours involve stairs, low ceilings and tight passages; the Wild Cave Tour requires fitness and appropriate clothing. Check the National Park Service for tour options, reservations, fees and conditions before visiting.

The National Park Service protects Jewel Cave’s rare formations, its bats and its cave ecosystem. Visitors help by never touching the crystals or any formations (oil from hands permanently damages them), following all white-nose-syndrome screening procedures (which may include leaving gear from other caves at home), staying on paved paths or with guides on wild tours, respecting bat hibernation seasons and closures, and following all rules. The cave’s formations and its bat populations are irreplaceable and sensitive. Protecting them sustains both the ecology and the crystalline wonder of Jewel Cave.

Jewel Cave tours involve stairs, cool damp air (49°F year-round), low ceilings and, on the Wild Cave Tour, tight crawling passages — wear a jacket, sturdy closed-toe shoes and comfortable clothes you don’t mind getting dirty (on wild tours). Tell rangers of any concerns; some tours are unsuitable for those with severe claustrophobia or limited mobility. Above ground, drive carefully on U.S. 16 and the park road. Respect the cold cave temperature, the physical demands of the various tours, and the need for appropriate footwear on damp cave surfaces.

Cave entry is by guided tour only; wild-cave participants must wear appropriate clothing and may not bring gear from other caves (white-nose syndrome prevention). Never touch formations or crystals — one touch causes permanent damage. Tours must be reserved; fees apply. Pets are not permitted in the cave and are restricted to developed surface areas. Drones are prohibited. Photography is allowed (no flash on some tours). Follow all white-nose-syndrome screening rules. Check the National Park Service for tour times, fees, reservation requirements and conditions before visiting.

The town of Custer about 13 miles east, Custer State Park, Wind Cave National Park and its prairie, Mount Rushmore, the Crazy Horse Memorial, and the rest of the southern Black Hills lie near the monument. The Black Hills define the region. Jewel Cave anchors the western southern Black Hills, a centerpiece of a South Dakota adventure, easily combined with Wind Cave National Park, Custer State Park, Mount Rushmore and Crazy Horse Memorial on a Black Hills circuit.

Book your cave tour in advance — especially in summer — and bring a jacket regardless of the season outside (the cave is always 49°F). Choose the Scenic Tour for an easy introduction to the crystals and formations, the Historic Tour for a lantern-lit adventure, or the Wild Cave Tour if you want to crawl into the cave’s undeveloped passages (wear clothes you don’t mind getting dirty). Never touch the crystals. Combine your visit with nearby Wind Cave National Park, Custer State Park and the southern Black Hills.