These are the World’s Most Extraordinary Caves

In the most impressive caves around the world, massive stalactites hang like daggers of ice, stalagmites rise majestically from the ground, and unusual creatures roam the depths. These astonishing feats of nature are rivaled by entire underground cities and chapels of worship carved out by hand.

Ready to add cave exploration to your bucket list? Grab your hard hat, hold your nerve, and join us on a journey into the center of the earth.

Son Doong Cave – Quang Bình Province, Vietnam

Geng Xu / Getty Images

At 656 feet wide, 492 feet high and almost 5.6 miles long, Son Doong is the world’s largest known cave.

First discovered by a Vietnamese man named Ho Khanh in 1991, it didn’t become world-famous until a group of British cavers explored it in 2009, uncovering a surrounding network of more than 150 caves.

Son Doong was created up to five million years ago by river water eroding away the limestone beneath a mountain. Inside, limestone formations – some as tall as office buildings – jut up from the earth, and streams of crystal clear water join an enormous lake colored an unearthly shade of blue.

The atmosphere in the massive cave is often surreal: where the limestone ceiling has collapsed, shafts of light pierce through the darkness, while mist formed at the cave’s entrance lends an eerie feel.

Waitomo Caves – Waitomo, New Zealand

MarcelStrelow / Getty Images

The Waitomo Caves in New Zealand get their name from the Maori words “wai,” for water, and “tomo,” meaning hole in the ground.

The caves formed over 30 million years ago and are home to thousands of glow worms whose luminous light turns the main cave into a magical fairy grotto. The creatures, called Arachnocampa luminosa, are unique to New Zealand.

The enormous Cathedral Cavern, filled with stalactites, stalagmites and other naturally sculpted limestone formations, can be traversed via boat or on foot. Adrenaline-seekers can explore the cave complex by swimming, crawling through passages, jumping off waterfalls, and scaling the cave walls using rope.

Blue Grotto – Capri, Italy

kparis / Getty Images

The Blue Grotto in Capri has been a popular tourist attraction since it was first introduced to the non-Italian world in 1826.

Famously, the water in the sea cave is an exaggerated shade of aquamarine, the result of the unique way the light shines through a small opening in the cliff face. The cave also touts a fascinating history: it was once used as the private swimming pool of Emperor Tiberius, who decorated it with statues of Roman sea gods.

Today, to access the cave, visitors must lie flat on the bottom of a boat as a boatman guides them through an entrance just over three feet high, pulling them along using a chain attached to the cave’s walls.

Caves of Heaven and Hell – Narlikuyu, Turkey

umutkacar / Getty Images

In Turkey, Heaven and Hell are both below ground.

The “Chasm of Heaven,” so named because of its otherworldly beauty, is 229 feet deep and 656 feet long, accessed via 452 steps. The remains of a 5th century Byzantine Chapel – initially dedicated to the Virgin Mary, and later briefly converted into a mosque – lie parallel with the 300th step.

Nearby, the “Gorge of Hell” is a 419-foot deep chasm where, according to myth, Zeus imprisoned the 100-headed fire-breathing monster Typhon. You can’t actually “go to Hell” by descending to the bottom of the cave, but you can view its depths from a platform extending 120 feet over the pit.

Postojna Cave – Postojna, Slovenia

thekopmylife / Getty Images

This cave filled with towering stalagmites includes its own 140-year-old railway. The two-mile train line leaves visitors at the start of a walking path, where sights include the 52.5-foot-high “Skyscraper” stalagmite and the 16-foot-high “Brilliant” formation, made from shiny white rock.

Visitors should look out for aquatic salamanders that, according to legend, are the offspring of a dragon that previously resided in the cave.

Cave of the Crystals – Chihuahua, Mexico

Alexander Van Driessche / Wikimedia Commons

Eighteen years ago, a crystal world was discovered below the earth’s surface in the Naica Mine in Northern Mexico.

Working at almost 1,000 feet underground, miners excavating a new tunnel came across a chamber containing some of the largest natural crystals ever found, measuring up to 36 feet in length and 13 feet in diameter, and weighing as much as 55 tons each. The crystals, which resemble massive light sabers, lie in interlocking diagonal formations across the width of the cave, creating a dazzling effect.

The caves were closed to the public until further notice in late 2017 and flooded with water to enable the crystals to continue to grow. But there’s a chance the caves will open to the public again in the coming years – and in the meantime, one of the crystals, measuring 32 inches, can be viewed at the Astro Gallery in New York City.

Derinkuyu Underground City – Derinkuyu, Turkey

maroznc / Getty Images

Located in central Turkey, Derinkuyu lives up to its name, which literally translates to “deep well.”

The earliest written reference to Derinkuyu dates back to 370 BC, but it’s believed this subterranean city is actually much older. Between the 7th and 11th centuries, when Arab invaders swept across the Anatolian plateau, Byzantine Christians took shelter underground. Family dwellings, animal stalls, food storage areas, schools, churches and even tombs were cut out of the area’s soft, easily carved volcanic stone. The last inhabitants, the Cappadocian Greeks, left in the early 1920s.

Today, visitors can explore the remains of these historic communities, housed in a space reaching nearly 279 feet deep.

Eisriesenwelt Cave – Werfen, Austria

Manuel Scheikl / flickr

This striking cave is not for the faint of heart. Not only is it accessed via a sloping, zig-zagging stairway 439 feet long, but inside, temperatures often dip below freezing.

The pain, however, is well worth the gain.

Using a lamp fashioned like an old miner’s lantern, guests explore the World of the Ice Giants, where massive ice formations glitter surreally, reflecting and refracting the lamplight. Cascades of water, frozen in motion, form fence-like tentacles that in places stretch from floor to ceiling.

At more than 26 miles long, the Eisriesenwelt cave is the largest natural ice and limestone cave in the world.

Fingal’s Cave – Staffa, Scotland

SteveAllenPhoto / Getty Images

According to legend, Irish giant Fionn mac Cumhaiil, better known as Finn McCool, built the Giant’s Causeway in Northern Ireland to access Scotland, so he could fight his Scottish counterpart, Bennandonner. The span crossing the Irish Sea has been lost to waves and time, but Fingal’s Cave, located on the Scottish side of the mythological walkway, remains.

Located on the island of Staffa, this 72-foot-fall and 270-foot-deep sea cave showcases interior walls formed from hexagonal columns of basalt, which rise out of the sea like pipes on a church organ.

The constant sound of the wind mixed with the ebb and flow of the water makes for a lovely musical score – hence the cave’s Celtic nickname, Uamh-Binn, or the “Cave of Melody.” The natural acoustics and the mysticism surrounding the cave have inspired many artists and musicians, from Felix Mendelssohn to Pink Floyd.

Jenolan Caves – Jenolan, Australia

chameleonseye / Getty Images

The Jenolan Caves, three hours from Sydney, date back more than 340 million years, and boast the extraordinary natural features that come with time.

There are actually nine caves in total, including the aptly named Diamond Cave – featuring glittering white crystal formations – and the River Cave, where deep aquamarine-colored pools are joined by an illuminated underground lake.

Courageous visitors can take an Adventure Caving tour, exploring the caves by navigating their small openings and tight passages.

Skocjan Caves – Skocjan, Slovenia

DavorLovincic / Getty Images

“Smithsonian” magazine has called Skocjan “the underground Grand Canyon” thanks to its extraordinary subterranean chambers. Chief among these is Martel’s Chamber, measuring 1,010 feet long and 479 feet at its highest point.

One of the most memorable ways to take in the sights here is by journeying across the Cerkvenik Bridge, which crosses over into Šumeca Cave. The bridge is suspended in the air, high above the Reka River, looking for all the world like an entry into Tolkien’s Middle Earth.

Sheets of rock millions of years old, as well as formidable stalagmites and stalactites, add to the otherworldly ambience.

Víðgelmir Cave – Hallmundarhraun, Iceland

Víðgelmir Cave / Víðgelmir Cave

The 5,250-foot-long Víðgelmir Cave lava tube in west Iceland formed when an eruption of lava developed a hard crust-like roof above a lava stream that continued to ooze. As the heat slowly died down, the cooling lava formed deposits in the shape of stalagmites and stalactites.

When the roof collapsed at the north end, it created two entrances into the tube, which visitors can today use to access wooden walkways passing lava walls that look freshly melted and cooled.

Perfectly formed lava stalactites protrude from the roof, while weirdly lifelike stalagmites march in orderly ranks across the cave floor. A red glow on pitted walls and stippled rock surfaces makes for a dazzling effect.

It’s believed that Víðgelmir Cave dates back to Viking times, as validated by bones and jewelry found by archaeologists in the cave in 1993.

Wieliczka Salt Mine – Wieliczka, Poland

Pavliha / Getty Images

Although not technically a cave, the Wieliczka Salt Mine deserves a place on this list.

It was mined for more than 700 years by thousands of miners, who didn’t only dig out salt deposits: just over 1,072 feet below the surface, they left behind chapels and religious statues carved out of rock salt, in tunnels that stretch 178 miles.

The mine’s tourist trail is packed with history, both real and imagined. According to legend, Princess Kinga brought salt to Poland, and a heavenly chapel was dedicated to her.