Giant Cave Systems

The low wooded hill at the edge of Luray sits in the Shenandoah Valley, under the Blue Ridge. On August 13, 1878, a party of local men noticed cool air breathing from a sinkhole on this hill. Read more After about four hours of digging, two of them lowered themselves on a rope and went in by candlelight.

They found chambers hung with stalactites, columns and draperies, and a shallow pool, Dream Lake, that mirrors the ceiling so cleanly it seems far deeper than it is. Two years later, a Smithsonian delegation reported: "It is safe to say that there is probably no other cave in the world more completely and profusely decorated with stalactite and stalagmite ornamentation than that of Luray."

Luray is a cave admired for its ornament. The next is measured by its size.

The Green River winds through the Kentucky forest above the longest known cave on Earth, more than 426 miles surveyed. Read more Four to five thousand years ago, people explored miles of it by the light of river cane torches, mining gypsum and other minerals. A popular story says a hunter named Houchin found the entrance while chasing a bear. It is a legend.

During the War of 1812, about 70 enslaved workers dug saltpeter here for gunpowder. In 1838, an enslaved 17-year-old named Stephen Bishop began guiding visitors. He crossed the Bottomless Pit, named the River Styx, and drew a map from memory that was used for more than 40 years. He was freed the year before he died.

In 1972, cavers joined Mammoth to the Flint Ridge system, near a lead Bishop's map had marked. No longer cave is known.

In the forested Ozark hills of north Arkansas, a stream pours out of a hillside as Blanchard Springs. The cave it comes from was never quite a secret. Read more Cane and wooden torches left inside have been dated to between about A.D. 200 and 1150. In the 1930s, local people called it Half Mile Cave.

In 1960, Hugh Shell and Hail Bryant of Batesville began exploring it in earnest, and found it ran far beyond half a mile: more than eight miles have now been surveyed. This is a living cave. Water still builds its flowstone and its rimstone pools, and each winter about half a million endangered gray bats hibernate here.

For decades the Forest Service ran it. In December 2025, Arkansas agreed to make it a state park.

On the desert escarpment of the Guadalupe Mountains, a road climbs to a dark opening in the rock. The limestone was once a reef along an inland sea. Most caves are carved by rainwater sinking from above. Read more This one was dissolved from below. Between four and six million years ago, water carrying hydrogen sulfide rose from the oil basin beneath, met oxygen, and became sulfuric acid. It hollowed out the Big Room, more than eight acres of floor, some 750 feet down.

Who found the entrance first? The Park Service answers plainly: "We will never know." Native people cooked and painted at its mouth long ago. Around 1898, a Texas-born cowhand named Jim White, about 16, began exploring it with a homemade wire ladder. It became a national park in 1930.

On summer evenings, hundreds of thousands of Brazilian free-tailed bats still spiral out of this entrance.

A few miles away, in the park's roadless backcountry, nothing on the surface hints at what lies below. For decades, Lechuguilla Cave seemed to be a 90-foot pit and a few hundred feet of dead end passage. Read more But in the 1950s, cavers heard wind roaring up through the rubble on its floor. In 1984, Colorado cavers won permission to dig. In May 1986, they broke through into great passages.

The survey has since passed 145 miles, and the cave descends about 1,600 feet. Like Carlsbad, it was dissolved by acid from below. It holds lemon yellow sulfur, gypsum chandeliers 20 feet long, and microbes thought to feed on the rock itself.

In 2012, climbers found a pit so tall that a park cave technician wrote: "imagine that a 51-story tower could fit inside!" Only about a hundred people a year go in.

In the desert foothills of southern Arizona's Whetstone Mountains, a small sinkhole is nearly all that shows from above. Read more In November 1974, two cavers, Gary Tenen and Randy Tufts, were searching these hills, in the park's words, "for a cave no one had ever found." In the sinkhole they felt warm, moist air leaking from a crack. Hours of crawling later, they stood in an untouched cave.

They kept it secret, telling the landowners, James and Lois Kartchner, only in 1978. When Tufts approached a state parks official in 1984, he would say only: "I cannot tell you." That official was later driven to the cave blindfolded. In 1988, Arizona bought the land, and the secret became public.

The cave opened in 1999 behind airlock doors that keep it wet. Each summer, more than a thousand female cave bats raise their young in its Big Room.

In the far north of California, dark lava flows and cinder cones spread across high sagebrush country on the flank of the Medicine Lake volcano. These caves are different. Read more Rivers of molten rock crusted over, flowed on beneath the crust, and drained away, leaving hollow tubes. More than 800 caves are known here.

This is also the homeland of the Modoc people, who carved more than 5,000 images into the rock at Petroglyph Point. In November 1872, the army moved to remove a band of Modoc. About 150 men, women and children took refuge in the lava. Led by Kintpuash, whom settlers called Captain Jack, 50 or 60 warriors held off as many as a thousand soldiers for five months.

In April, at a peace meeting, Kintpuash killed Gen. Edward Canby. In October 1873 he was hanged, and his people were exiled to Indian Territory.

High in the forested Siskiyou Mountains of southern Oregon, a six-story chateau stands at the mouth of a cave. This cave is cut not in limestone but in marble, rare among the nation's park caves. Read more The rock began as limestone on the Pacific seafloor, and was transformed into marble as it was carried onto the continent.

The Takelma people may have known the cave. In late November 1874, Elijah Davidson followed his dog Bruno, in pursuit of a bear, into the dark. His last match went out. Promoters soon followed, and one claimed the cave ran 22 miles. Its known passage is closer to three.

The poet Joaquin Miller called it the "Marble Halls of Oregon," and in 1909, President Taft made it a national monument.

At the eastern foot of Nevada's Snake Range, sagebrush slopes rise toward Wheeler Peak. The cave lies beneath them. People knew this entrance long before ranchers did. Read more Human bones found beneath it, about 800 years old, were almost certainly placed there on purpose, perhaps for burial.

There are more than 40 accounts of the cave's discovery. The most likely is that the rancher Absalom Lehman, or one of his hands, found it in 1885. That April, the newspaper in Ely reported: "Stalactites of extraordinary size hang from its roof." Lehman guided the first visitors himself, and early parties broke formations as they went.

The cave's rarest feature is its shields, flat paired discs of calcite that grow out of cracks in the rock. There are more than 500 here. In 1922, President Harding made it a national monument.

In the steep, narrow American Fork Canyon of Utah's Wasatch Range, three caves sit high on the canyon wall, about a thousand feet above the river. Read more In 1887, Martin Hansen found the first, and within years it had been damaged by an onyx company and by souvenir hunters. In 1913, two teenagers found a second cave, and its entrance was lost again.

In August 1921, Vearl Manwill rediscovered it. That October, Hansen's son and grandson spotted a third cave through binoculars while hunting deer. Martin Hansen, then 74, was the first to enter. Tunnels later joined all three.

Their walls carry helictites, formations that twist as if gravity did not apply, some tinted green and yellow by traces of nickel. In 1922, President Harding protected the caves for what his proclamation called their "unusual scientific interest and importance."

Ponderosa pine covers the southern Black Hills here, much of it regrowing after a fire in the year 2000. Beneath lies the second longest cave in the United States. Read more In 1900, two prospecting brothers, Frank and Albert Michaud, found a small hole blowing cold air. They widened it with dynamite and found walls lined with calcite crystals that sparkled like jewels in their lantern light.

They sold crystals and tried running tours, which failed. In 1908, President Theodore Roosevelt made it a national monument, the first cave ever given that status. Yet by 1959, only about two miles were known. That year, two rock climbers, Herb and Jan Conn, began exploring. Over two decades they mapped some 65 miles.

The survey has now passed 220 miles, all beneath about four square miles of land. The air the cave breathes suggests most of it is still unfound.

Where prairie meets pine at the edge of the Black Hills, bison graze above one of the oldest caves known. The Lakota have long known this opening as the place where the earth breathes. Read more In the Lakota emergence story, the people once lived underground. Those lured to the surface could not return, and became the first bison.

Congress had taken the Black Hills from the Lakota in 1877. Four years later, the brothers Tom and Jesse Bingham heard wind whistling from a hole hardly a foot across. In 1890, young Alvin McDonald began exploring by candlelight, and wrote in his diary: "Have given up the idea of finding the end of Wind Cave."

In 1903, it became the first national park in the world created for a cave. More than 167 miles are mapped. The end has still not been found.