58 Fun Facts About Caves

Most of the world's caves are formed by the slow dissolving of which rock?

Limestone (calcium carbonate) dissolves in rainwater charged with carbonic acid, which eats along cracks and bedding planes; the resulting sinkhole-pocked landscape is called karst.

What is the name for the scientific study of caves?

Speleology. Édouard-Alfred Martel, its "father", and his crew were the first to explore many caves that are now famous tourist attractions.

Which cave formation builds up from the floor where mineral-rich water drips?

Stalagmite. Each drip leaves a little calcite behind, and when a stalagmite grows into the stalactite feeding it, the pair join into a column.

Which cave system in Kentucky has the greatest total length of surveyed passage of any in the world, over 675 km?

Mammoth Cave. In 1972 cavers found a passage linking it to the even longer Flint Ridge system next door, joining the two into one vast network.

In which country is Sơn Đoòng, the cave with the largest known passage in the world?

Vietnam. Hồ Khanh found the entrance in 1990 while out gathering wood, then lost track of it in the jungle and only found it again in 2008.

Bracken Cave near San Antonio, Texas, is the summer home of the largest colony of which animals on Earth?

Mexican free-tailed bats. Up to 20 million roost there each summer, and in 2014 San Antonio and conservation groups bought land beside the cave to keep a housing development away.

Waitomo Cave in New Zealand is famous for a ceiling lit by thousands of what?

Glowworms. They are the larvae of a fungus gnat, dangling sticky silk threads that snare insects drawn to their light.

What are cave visitors told to do to enter the Blue Grotto on the island of Capri?

Lie flat in a small rowboat. The entrance is only about a metre high, so the boatman pulls the boat through on a metal chain fixed to the cave wall.

In 2018, twelve boys and their football coach were trapped for over two weeks in the Tham Luang cave in which country?

Thailand. Divers found the Wild Boars alive after nine days, and all 13 were brought out between 8 and 10 July, the boys sedated for the dive.

The Paleolithic paintings of Lascaux, with its Hall of the Bulls, are in which country?

France. Four teenagers found Lascaux in 1940, but crowds of visitors brought damp and mould that damaged the paintings, so it closed to the public in 1963.

Which Siberian cave gave its name to an extinct group of archaic humans identified from a finger bone in 2010?

Denisova Cave. The finger bone had no telltale features, so the new human group was recognised from its DNA alone.

Fingal's Cave, the sea cave linked to Mendelssohn's Hebrides Overture, is on which Scottish island?

Staffa. The cave's walls are hexagonal basalt columns that formed as an ancient lava flow cooled, like those of Northern Ireland's Giant's Causeway.

Cave-dwelling animals such as blind fish and pale salamanders that cannot live outside caves are called what?

Troglobites. Some blind cavefish still belong to the same species as sighted river fish, and the two can interbreed.

Which blind, pale European cave salamander can survive for years without eating?

The olm. When heavy rains flushed olms out of their caves, locals took the pale, eyeless creatures for the offspring of a dragon.

The Cave of Altamira, famous for its Paleolithic bison paintings, is in which country?

Spain. Sautuola's daughter María spotted the painted ceiling in 1879, but experts scorned the find until a leading sceptic published a mea culpa in 1902.

The word "karst", for landscapes of sinkholes and underground drainage, is associated with a plateau in which country?

Slovenia. Geologists took Karst, the German name for the Kras plateau it shares with Italy, and applied it to similar landscapes elsewhere.

India's Ajanta Caves, rock-cut monasteries full of ancient murals, were built by followers of which religion?

Buddhism. A British officer on a tiger hunt reached the caves in 1819, and as word of his find spread, visitors followed.

Lechuguilla Cave and Carlsbad Cavern in New Mexico were carved from below by what, formed from gas rising off oil deposits?

Sulfuric acid formed when hydrogen sulfide mixed with groundwater and ate upward; most caves are dissolved from above by rainwater.

Kazumura Cave in Hawaii is the world's longest example of what kind of cave?

Lava tube. It formed when the surface of a lava flow crusted over while molten rock kept flowing beneath, then drained away to leave a tunnel.

The Cave of the Crystals beneath the Naica mine in Mexico holds beams up to 11 metres long of which mineral?

Gypsum. The crystals grew as hot, mineral-rich groundwater slowly cooled, and the air is so hot and humid that people without cooling gear last only about ten minutes.

The Sarawak Chamber, the largest cave room by area, lies in Gunung Mulu National Park on which island?

Borneo. A scientist followed a stream upstream to the cave's mouth, and cavers who went in later found the chamber.

Which Ardèche cave, found in 1994, is the subject of Herzog's 'Cave of Forgotten Dreams'?

Chauvet. Only a select few scientists are allowed inside, so Herzog needed the culture minister's green light to film there.

Cueva de las Manos, a UNESCO site of stencilled hands, is in which country?

Argentina. Hunter-gatherers drawn by herds of guanacos made the stencils, and they painted galloping guanacos beside the hands.

Krubera and Veryovkina, the two deepest caves known in 2018, lie in which mountain range?

Arabika Massif, Caucasus. In September 2018 a rainstorm flooded Veryovkina's lower levels while a team was deep inside, and they narrowly escaped.

Rising Star Cave in South Africa's Cradle of Humankind yielded fossils of which hominin species, announced in 2015?

Homo naledi. The chamber was so hard to reach that Lee Berger advertised on Facebook for skinny scientists who weren't claustrophobic, and six women took the job.

Derinkuyu, an underground city carved into soft volcanic tuff and able to shelter 20,000 people, is in which region of Turkey?

Cappadocia. The city lay forgotten until 1963, when a local man renovating his house broke into its passages.

In Homer's Odyssey, which Cyclops traps Odysseus and his men in his cave?

Polyphemus. Odysseus says his name is Noman, so when the blinded giant cries that Noman is killing him, the other Cyclopes think no one is hurting him.

Movile Cave in Romania, sealed off for 5.5 million years, hosts an ecosystem based entirely on what?

Chemosynthesis. In air with about half the normal oxygen, bacteria draw energy by oxidising gases such as methane, and the cave's whole food web depends on them.

Clay dated in 2006 to about 340 million years made which caves west of Sydney the oldest known open caves?

Jenolan Caves. Geologists had estimated them at 90 to 100 million years old until a clay-dating method developed for oil exploration pushed the figure past 340 million.

Cenotes, the sinkholes the ancient Maya used for water, are concentrated on which peninsula?

Yucatán. A ring of cenotes there marks the buried rim of the Chicxulub crater, left by the asteroid impact most scientists blame for wiping out the dinosaurs.

Cave bears, which died out around 24,000 years ago, differed from brown bears in which way?

They were almost entirely herbivorous, studies suggest, and their bones, piled up in caves, were once taken for the remains of dragons.

Which cave near Werfen in Austria is the largest ice cave in the world?

Eisriesenwelt. Cold winter air pouring in through its entrance freezes the snowmelt that seeps inside, so its ice formations change every year.

Gough's Cave, where a near-complete 10,000-year-old human skeleton was found in 1903, opens onto which Somerset landform?

Cheddar Gorge. DNA from that skeleton, Cheddar Man, suggests he had dark skin and blue eyes, overturning the assumption that people in Europe quickly evolved pale skin.

Puerto Princesa's underground river, voted one of the New 7 Wonders of Nature, flows beneath which Philippine island?

Palawan. The river flows straight into the sea, and seawater pushes into the lower part of the cave.

The Batu Caves near Kuala Lumpur, with a giant statue at the foot of the steps, host which Hindu festival?

Thaipusam. Devotees climb the caves' 272 steps to pray at the cave shrine of Lord Murugan, the god the festival honours.

Ruby Falls, an underground waterfall deep inside Lookout Mountain, is in which city?

Chattanooga. A railway tunnel had sealed the old cave's entrance, and efforts to reach it again led to the waterfall's discovery in 1928.

The Miao Room, announced in 2014 as the largest known cave room by volume, is in which country?

China. A team mapped it with 3D laser scanners in 2013, and the data showed it beat the Sarawak Chamber by volume.

Which director executive-produced the 2011 3D cave-diving thriller Sanctum?

James Cameron. The film drew on a real-life ordeal of its co-writer, the caver Andrew Wight.

Which cave formation grows in curling shapes that seem to defy gravity?

Helictite. Water feeds each one through a tiny central canal, and capillary forces are thought to let its tip grow in any direction, even upward.

In caving, what is a passage flooded to the ceiling, forcing a dive, called?

Sump. In 2018 cavers who reached the bottom of the Veryovkina cave found their way on blocked by a sump at the water table.

Which enslaved guide mapped and named many features of the world's longest cave in the 1840s and 1850s?

Stephen Bishop. He and a visitor crossed the Bottomless Pit, opening miles of new passages, and in 1842 he drew a map of the cave from memory.

Which teenager explored Carlsbad Cavern with a homemade wire ladder in 1898 and named its Big Room?

Jim White, a 16-year-old cowboy, climbed down with a wire ladder in 1898 after seeing bats pour from the entrance; he named the Big Room, nearly 1,220 metres long.

In Plato's allegory of the cave, what do the chained prisoners take for reality?

Shadows on the wall. Socrates adds that the prisoners would kill anyone who tried to free them and lead them up out of the cave, if they could.

The Jeita Grotto, a cave toured by boat along the underground Nahr al-Kalb river, is in which country?

Lebanon. The grotto closed to visitors in 1978 during the civil war and did not reopen until 1995.

The Reed Flute Cave, lit in bright colours and inscribed with Tang-dynasty writings, is a landmark of which city?

Guilin. People took shelter in the cave during the war of the 1940s, and it officially opened to tourists in 1962.

Which cave near Mecca do Muslims revere as the site of Muhammad's first revelation?

The Cave of Hira. Muslim tradition holds that the angel Gabriel appeared to Muhammad there and commanded him to recite, the start of the Quran.

The Cave of the Apocalypse, where St John is said to have received the visions of Revelation, is on which Greek island?

Patmos. In Revelation, John writes that he was on the island 'because of the word of God and the testimony of Jesus'.

Which former navy diver died delivering air tanks during the 2018 Tham Luang rescue?

Saman Kunan. The former Navy SEAL ran out of oxygen on his way back after placing air tanks along the route to the boys, and was posthumously promoted seven ranks.

Which ancient manuscripts did Bedouin shepherds first find in caves near Qumran in the late 1940s?

The Dead Sea Scrolls. The Bedouin sold the first scrolls to antiquities dealers, and they proved to include the oldest known manuscripts of the Bible.

Which Mark Twain novel made a cave near Hannibal, Missouri, so famous that it was renamed Mark Twain Cave?

The Adventures of Tom Sawyer. Twain explored the cave as a boy, and in 2019 researchers confirmed his real name, Sam Clemens, written on its wall.

The Salle de la Verna, a cave chamber 194 metres high, is in which mountain range?

The Pyrenees. In the 1950s a power company dug a tunnel to the chamber to capture its underground river, and visitors now walk in through that tunnel.

A doctor once moved patients into huts inside a Kentucky cave, believing its air would cure which disease?

Tuberculosis. The experiment failed, and the doctor, John Croghan, later died of tuberculosis himself.

In the Bible, who bought the Cave of Machpelah in Hebron as a family burial place?

Abraham. Genesis says he paid 400 shekels of silver for the cave and its field to bury his wife, Sarah.

Sof Omar, a famous cave system in the Bale region, is the longest cave in which country?

Ethiopia. The Web River vanishes into the cave at one entrance and reappears about a kilometre away.

Which caves, 24 hand-carved chambers of unknown origin, did farmers find in 1992 by draining village ponds?

The Longyou Caves. Locals had called one of the ponds bottomless for generations, and four villagers pumped for 17 days to empty it.

What term do cavers reserve for a hollow formed within moving ice?

Glacier cave. Most start as water runs into or under the glacier, and the flowing water melts out a hollow.

Which Arizona cave did two cavers keep secret after squeezing in through a crack at the bottom of a sinkhole?

Kartchner Caverns. Fearing vandals would damage the cave, the discoverers stayed quiet until the land could be protected, and it opened as a state park in 1999.

Tulum and the flooded cave systems around it lie in which Mexican state?

Quintana Roo. Divers exploring the flooded caves near Tulum have found skeletons of some of the earliest known people in what is now Mexico.