This article was originally published on ScientistPlus
If your first thought when imagining a cave is darkness, creepiness, and maybe even claustrophobia - you're not alone. Luckily, we don't have to travel thousands of miles, plunge carefully to the earth's deepest corners, and potentially risk our lives to see the treasures these caves have to offer. From cursed findings to scientific phenomenons, keep scrolling for some groundbreaking cave discoveries.
A Cursed Discovery
Hikers supposedly found this eerie effigy in the Catskill Mountains of New York, where it may have been created as a malicious act of vengeance or as a craft project at a summer camp for the dark arts. The object has now taken on a life of its own, complete with loads of stories about paranormal events that manifested in the hikers’ home after removing it from its cave. Think strange footprints, putrid smells, and ghosts.
Wherever the figurine came from, why remove it from where it was found? Seems like an invitation for bad dreams and anxiety, no matter how many times you might encircle it in salt.
The Secret and Elite Club
Located in Buckinghamshire, Southeast England, the Hellfire Caves were used as a meeting place for 18th-century politician Francis Dashwood and his secret society. Dashwood’s elite pals (one chamber is named ‘Franklin’s Cave’ for Benjamin Franklin) would gather here to engage in libertine exploits—rumored to have included occult rituals and group sex—that would have scandalized conservative British society at the time. The stories surrounding this Hellfire Club have lasted long enough to make the caves a popular tourist site today.
Reaching the cave’s meeting room required visitors to cross an underground river referred to as Styx, so named after the boundary between earth and the Underworld in Greek mythology. And if that wasn't eerie enough, wait until you see the next mystifying cave discovery.
So Many Crystals
Located within a mining complex in Chihuahua, Mexico, the selenite crystals in the Cueva de Los Cristales extend up to 37.4 feet and weigh up to about 12 tons. Anxious to see these stunning structures in person? Unfortunately, the Cave of the Crystals is not open to tourists. That said, it might be worthwhile to go back to school for a degree in speleology (the study of caves) just for the chance to observe these scintillating formations.
After you get a permit to enter the cave, you’ll need to bring plenty of water, as well as a specialized, refrigerated bodysuit. Air temperatures in the cave can climb to a balmy 136 degrees Fahrenheit.
Marine Cemetery
Madagascar’s underwater Aven Cave is filled with the bones of extinct megafauna, which were once overflowing on the island nation. The remains of land-dwelling species like elephant birds and gorilla-sized lemurs may have washed into the flooded cave; the bones were so numerous that they covered the cave’s floor when they were first discovered. Madagascar’s mass extinction event has long-puzzled paleontologists who hope to analyze the cave’s bones for signs of human butchering.
If you’re an experienced diver, you might be able to visit the underwater museum (yes, that’s a thing) associated with Aven Cave, though it is periodically closed for research. But this is hardly the most extreme cave on this list.
The Deepest Pit in the U. S. Is the Stuff of Nightmares
This entry point may look relatively unimpressive, but it’s hardly for the faint of heart. It provides access to Northwest Georgia’s Ellison’s Cave, one of the most renowned pit caves in the United States. Rather than entering through more standard horizontal passages, daring adventurers must enter pit caves through lengthy vertical shafts. Ellison’s Cave features the aptly named Fantastic Pit, a 586-foot drop that claims the title of the deepest pit in the contiguous U.S. At only 440 feet, the same cave’s Incredible Pit might feel comparatively inadequate.
Negotiating the entrance isn’t without risk, as multiple Ellison’s Cave spelunkers have suffered either severe injury or even death following unanticipated trouble with their equipment.
An Ancient Lava Tube
Iceland’s Víðgelmir is a lava tube. While that might make it sound like some kind of decorative knickknack made in the 80s, it’s actually a fascinating structure made over 1,000 years ago. Lava tubes, also known as pyroducts, form when a lava stream’s surface hardens, creating a tube-like crust surrounding its molten core. When the liquid lava flows out, the hardened crust remains, leaving an impressive cave to be enjoyed for millennia.
Vikings apparently inhabited Víðgelmir at one point during the Middle Ages, which is actually not long after the pyroduct’s hypothesized formation. And if that's not enough, wait until you read about the next terrifying cave discovery.
A Terrifying Record-Breaking Snake
Responsible spelunking is generally a safe hobby, though it’s not entirely without risks. Cavers might perish in sudden floods, sustain head trauma from falling rocks, or, occasionally, encounter 33-foot snakes that would make the villain in the film Anaconda swim away in panic. Construction workers discovered this giant reptile in 2016 after executing a controlled explosion in a Northern Brazilian cave. Though it’s difficult to accurately confirm if the snake is the largest discovered in modern history, it may very well be the most intimidating.
The encounter with the snake was prompted by the construction of the Belo Monte dam, situated on a tributary of the Amazon river. It appears the unfortunate reptile was only one of the dam’s many casualties, as environmentalists predict that the dam will lead to the extinction of hundreds of unique fish species.
Not as Calm as It Looks
Capri’s Blue Grotto is perhaps the world’s most famous sea cave, and for good reason. The dramatically low arch serving as its entrance—only about three feet high—creates the perfect lighting conditions for the almost unearthly blue waters from which the cave gets its name. Though Roman emperors once used the cave as a private swimming hole, visitors today can’t follow suit, unfortunately, and are forbidden from exiting the small boats permitted inside.
Though the colors of the Grotto may be the definition of serene, entrance to the cave can be anything but. Coming in during choppy waters can have dangerous consequences, with one visitor in 2011 suffering a broken neck. And that's not the worst one yet.
An Ancient Home
To the untrained eye, these piles of stalagmites—the rock formations that extend upward from the floor of a cave—may have simply collapsed. But paleolithic archaeologists believe they were intentionally arranged this way by Neanderthals inhabiting the Bruniquel Cave in southwestern France. The piled stalagmites are estimated to be over 176,000 years old, dating to when Neanderthals may have sought out caves as shelter from what was a particularly cold climatic period.
Construction of the piles is all the more impressive given that they were located in a part of the cave far removed from any trace of sunlight; thus the sophisticated Neanderthal builders must have used their own independent sources of light to see.
The Cave Discovery That Changed Everything
Owing to their dry atmosphere, caves have served as fossil libraries for many extinct species that we otherwise might not have known about. This foot, found in a New Zealand karst cave, once belonged to a giant, flightless bird called the moa. It reached heights of up to 12 feet and weighed up to 500+ pounds. This moa may have met its demise after slipping into the cave via a vertical shaft, which was hardly an ideal circumstance for a wingless bird.
Once abundant throughout New Zealand, moa went extinct within an estimated 200 years after the arrival of the Maori, New Zealand’s indigenous human inhabitants. And believe it or not, this is not the most extreme cave discovery on this list.
A Long Time Fascination
The advent of show caves is sometimes mistakenly dated to the 1900s, which is understandable given that century’s technological leaps. But show caves have actually existed for far longer than you might expect, as proven by the pictured Reed Flute cave situated near Guilin in Southeastern China. Inscriptions from curious tourists can be found in this cave dating back to the Tang Dynasty, which lasted from 618 to 907 CE.
Though the cave’s public appeal today can be attributed to its beautiful artificial lighting, it once served as a bomb shelter during the Second Sino-Japanese War. Charming, huh?
It’s Alive
Residents of Northern Arkansas have explored the Blanchard Springs Caverns for nearly 100 years. But it likely looked a bit different when they first discovered it, if even in a very minute way. Its speleothems—i.e. cave structures including stalactites, stalagmites, and straws—continue to slowly change as water drips into the cave and calcite deposits accumulate over time. Though the growth is gradual, it may be worth the wait: The cave’s famed ‘Giant Flowstone’ is a spectacular, almost floral-esque sight to behold.
Blanchard features over eight miles of passage, which may sound extraordinarily lengthy to the uninitiated. But this pales in comparison to Kentucky’s Mammoth Cave which continues for an astonishing 400 miles.
An Unexpected Inspiration
Classical music fans should definitely add Scotland’s Fingal Cave to their bucket list. Waves crashing into the sea cave’s basalt columns create an unusual soundscape, which was distinct enough to inspire one of the classical world’s most bellowed compositions: Felix Mendelssohn’s concert overture "The Hebrides." The piece includes woodwinds, brass, percussion, and strings to successfully bring to life the cave's inside with the unpredictable violence of the Scottish sea.
The cave’s memorable auditory and visual features have since inspired countless other artists and writers, ranging from Jules Verne to Pink Floyd. Some caves can be truly inspirational, whereas others inspire nothing but fear - read on to find them, if you dare.
Mysterious Cave Creatures
The fresh and brackish waters found in some caves have led to the evolution of cave fish, for which there are hundreds of different species. Cave fish exhibit a high degree of troglomorphism, meaning, like deep-sea fish, they’ve evolved to live in an environment without light or abundant food sources. They may navigate by sensing vibrations in the water or by using their senses of taste and smell; their metabolic rates are usually quite slow, allowing them to survive famine.
For some fish species, such as catfish, both a more typical above-ground version and a cave-adapted version of the species may exist, though the cave dwellers are typically much smaller than their cousins.
A Cave With Health Benefits
Though a number of historical salt mines have been revamped into popular tourist attractions, few use simple lighting mechanisms as effectively as Salina Turda, and few are as well preserved. Located about a 10-minute drive from the picturesque Transylvanian city of Turda, the mine contains a haunting echo chamber, an underground lake, and fascinatingly archaic machinery once used to extract and transport the salt from the cave to the surface.
Today Salina Turda is visited not only for its spectacular views but also as a center of halotherapy, a scientifically unproven salt exposure treatment for lower respiratory diseases.
You'll Never Guess What Those Lights Are Made of
The New Zealand glowworm, known scientifically as arachnocampa luminosa, creates a brilliant spectacle on the ceilings of the Waitomo Caves on New Zealand’s North Island. After marveling at the multi-level cave’s ‘Cathedral’ formation, its 50-foot vertical limestone shaft, and ancient dining hall, visitors can float through the cave’s underground waterways while admiring the bright overhead lighting, courtesy of the worms. Who says Venice offers the most romantic boat ride in the world?
Glowworms aside, subterranean water pools inside the Waitomo Caves are also home to another uniquely Kiwi species, the New Zealand longfin eel, a traditional food source for the Māori.
Pray for Rain
Caves have long served as both shelter and art canvas for human beings, but a cave’s haunting acoustics might also make it an ideal site for religious worship. At least, that’s what ancient Maya of the Yucatan Peninsula thought; the cave pictured here was apparently used as an alter to ask for water. In 2019, researchers found over 150 well-preserved buckets and incense burners that featured artistic depictions of Tlaloc, a central Mexican rain god.
Archaeologists were led to the pottery remnants via a tip from locals, who had discovered the cave and its contents 50 years earlier, and fortunately hadn’t forgotten about it.
As Old as Time Itself
If diverse wildlife, haunting grasslands, and peaceful plateaus aren’t quite enough to draw nature enthusiasts to South Africa, the Cango Caves might tip the scales of curiosity. Formed from limestone in the Precambrian era (the oldest era of earth’s history), the caves once served as human shelter in the Stone Ages, and are now recognized as one of the iconic sites of the Swartberg Mountains. Among the most memorable features in the Cango Caves are its special stalactites, which look like the hanging branchlets of willow trees.
While Cango is an obvious draw for the average tourist, it may not be the right system for diehard spelunkers; visitors can enter its caves only via guided group tours, which cover only one fourth of the system’s total area.
To Mine or Not to Mine?
Humans are believed to have begun mining over 40,000 years ago, and the debate over how to responsibly utilize caves is almost as old as caves themselves. Some caves are suited to be either show caves, highlighted for their aesthetic and educational value to the public; nature preserves, protected for their ecological and scientific importance; or, of course, sources for minerals. The need for resources often wins out, but this may change as environmental awareness grows.
The pictured cave in Onondaga Cave State Park was initially developed as both a potential show cave and a source of flowstone, a material that was used to build furniture at that time.
One of Humankind's Old Homes
While most caves are fairly inhospitable (think chilly and dark), some have historically served as shelter to various animal species, including humankind and its distant cousins. Liang Bua, a limestone cave situated on the Indonesian island of Flores, was the site of a spectacular discovery in 2003 when researchers found the remains of a diminutive, ancient human species standing a mere 3’7”, who dwelled in Liang Bua about 50,000 years ago. Who knows what might be discovered next in another cave amongst Indonesia’s 17,000+ islands.
Can’t make it all the way to the Savu Sea to see Liang Bua for yourself? No problem. You can still geek out via a 3D digitization of the cave courtesy of the Smithsonian.
White Carrot Cave
While the Buckeye State isn’t exactly well known for its abundance of breathtaking nature, perhaps that should change. The Ohio Caverns span two miles in length and should be part of any ‘must-see’ list of sites in the Midwest. The Caverns are particularly famed for the Crystal King, the largest stalactite in Ohio, which hangs to nearly five feet in length and is estimated to weigh over 400 pounds.
Impressive though the Crystal King may be, it’s hardly the largest stalactite in the world. That honor belongs to a 92-foot behemoth in Brazil’s Gruta do Janelão cave.
The Austrian Ice Palace
It’s no surprise that one of the world’s most hauntingly beautiful ice caves can be found in the Austrian Alps, at an elevation of over 5,400 feet. Eisriesenwelt, a limestone ice cave, maintains its ice structures year-round; temperatures inside the cave remain quite nippy, summer or winter. That said, the cave is only open to visitors from May through October each year, with visitation peaking in the summer and dwindling considerably by the end of autumn.
Despite its rustic vistas, Eisriesenwelt is conveniently located less than an hour away from picturesque Salzburg (the birthplace of Mozart) and is easily accessible by public transit.
Scuba Diving in the Dark
Always check weather reports before entering a cave, particularly if you live in a monsoon climate. In 2018 an assistant football coach in Thailand learned this lesson the hard way when he brought 12 of his youth players on a post-practice spelunk. The cave flooded, leaving the group trapped for over two weeks. The dramatic rescue effort was followed carefully the world over, and involved over 10,000 people. Two Thai Navy Seals died as a result of the operation.
A common refrain in team sports is that no one usually likes the team coach, but everyone usually likes the assistant coach. But this incident might force us to reexamine that dichotomy. There is, apparently, a reason why assistant coaches are not placed in key decision-making roles.
A River Runs Through It
Central Europe is home to a number of captivating caves, but the Škocjan Caves in Slovenia are perhaps the region’s most vaunted hollows of all. The Reka River disappears into the cave system at the breathtaking Big Collapse Doline gorge, where it then flows underground for a full 21 miles, winding through an enormous underground canyon before reemerging on the other side. This unusual feature provides nutrients for a subterranean wetland ecosystem.
Škocjan Caves are considered to be of such aesthetic, geological, and archaeological value that they are among a relatively small number of caves honored as a UNESCO World Heritage Site.
A Cave Full of Inspiration
As the home of sartorial greats like Cristóbal Balenciaga and Manolo Blahnik, Spain is well known for its influence on fashion. But just how long does that legacy date to? Try 115,000 years, give or take. The Cave of Los Aviones, adjacent to Cartagena, served as a design studio for fashion-conscious Iberian Neanderthals, who created painted beads from seashells. Anyone lucky enough to have dipped into the exquisite green-blue waters of the Murcian coast can understand why the Neanderthals felt so inspired.
The term ‘Neanderthal’ has long been used as a slur against persons of lesser intelligence. If anyone is ever so uncouth as to toss the term at you, politely inform them that you’re happy to be among such creative company.
The Case of a Curious Goat
In the late 1940s, a local Bedouin boy was herding goats on a plateau above the Dead Sea. One goat wandered off into one of the Qumran Caves. While in pursuit of his stray animal the boy discovered the Dead Sea Scrolls, the oldest surviving manuscripts of the Hebrew Bible. The next time your dog runs away while you’re on a walk, remember that your enterprising four-legged friend might stumble onto a priceless artifact.
The Qumran Caves are as geopolitically contentious as they are religiously significant. Though they were the site of a milestone discovery in Jewish history, they are located in the occupied Palestinian territories and administered by the Israel Nature and Parks Authority.
Parietal Poetry
The Lascaux cave in southwest France is one of the world’s foremost destinations for fans of artistic renderings on stone, known as parietal art. The paintings at Lascaux serve to not only remind us of humankind’s critical relationships with animal species, but also demonstrate an impressive level of skill, including the precocious use of perspective. The cave’s immense popularity ultimately proved problematic, as carbon dioxide and contaminant exposure threatened its paintings with erosion. They were subsequently closed to the public in 1963.
Similar to the Qumran Caves, Lascaux was disovered when a French teenager went in pursuit of his dog, who had fallen through a hole into the cave.
A Cave Symphony
Zhaishan Tunnel was constructed during the early to mid-1960s as a naval base for the Republic of China (Taiwan), following the Second Taiwan Strait Crisis. The underground site is now the home of the annual Kinmen Tunnel Music Festival, which brings together classical musicians to perform on floating stages. The man-made cave’s acoustics uniquely capture the notes of Mozart, Beethoven, and Bizet, and the festival draws thousands of spectators from around the world.
While geographical relations remain tense, they seem to make the most of a difficult situation. Perhaps one day, musicians from all over can come together to fill the cave with shared music.
That Can’t Be Its Real Name
Not all cave contents are universally admired. These hanging substances, referred to as ‘snottites’ or ‘snoticles’, are comprised of multi-layered bacterial sheets which form as a byproduct of dripping sulfur in caves. The unsettling material is commonly found in the Tabasco region of Mexico as well as the Marche province of Italy, but observers have opined that they look more suitable for a science fiction horror film, a la Alien.
Those who are easily revolted by nasal fluids and any reminder thereof can instead refer to this icky substance by one of its scientific names, like acidithiobacillus thiooxidans. But good luck pronouncing that.
Fit for a Princess
The Philippines’ Puerto Princesa Subterranean River National Park may not be host to the world’s longest underground river—that honor belongs to Mexico’s Sistema San Actun. But it’s indisputably home to one of the world’s most dramatically beautiful caves, which, in addition to its underground river, also boasts waterfalls, an enormously large open chamber, and a flowing exit into the West Philippine Sea. The breathtaking terrain was honored with inclusion in the New 7 Wonders of Nature, among more famous entries like the Iguazú Falls in South America or Vietnam’s Hạ Long Bay.
This system also has the distinction of being one of the few caves in the world to be represented as a Google Doodle, which depicted one of the cave’s dramatic entry points.
Spectacular Submarine Sinkholes
Small pools of water can be a transfixing site found within caves. How about caves completely submerged by seawater? These ‘blue holes’ were formed when earth’s atmosphere warmed up at the end of an ice age, causing sea levels to rise and destroying the roofs of limestone caves. Blue holes can extend to depths of hundreds of feet, which accounts for their strikingly dark blue color next to more serene, turquoise waters.
Fancy exploring a blue hole? Do so at your own risk. The most famous blue hole in Egypt’s Sinai Peninsula has earned the moniker ‘Diver’s Cemetery,’ and is reportedly the site of numerous diving fatalities each year.
Let’s Get This Show Under the Road
Arizona’s Kartchner Caverns State Park features a fabulous show cave—which is a cave of considerable aesthetic appeal that is typically well lit and open to the public for independent or group tours. The caverns were discovered in 1974 by two recreational spelunkers, who followed the scent of bat guano to find underground passages exceeding two miles in length. The discovery was kept secret from the public until 1988, when ownership of the caves was transferred from private to state hands.
Though the site has been developed into a popular attraction, parts of the system are closed during the summer, when it’s used as a roosting (sleeping) ground by bats.
A Photographer’s Dream
Situated in Northwest Morocco between the Rif and Middle Atlas mountain ranges, Gouffre de Friouato (‘Friouato’s Chasm’) is a partially explored cave system highlighted by curtain-like rock formations, limestone tables, the stunning skylight pictured here, and a hypothesized underground river. The caves reach a known depth of around 900 feet, though they may extend even further, possibly down to 1600+ feet. The system is accessible from the nearby city of Taza, located less than 20 miles away.
After exploring the cave, visitors can change out of their dusty spelunker rags before visiting the Great Mosque of Taza and marveling at its enormous Marinid chandelier.
Stunning Sinkholes
The Yucatán Peninsula has long been a major tourism destination due to its beautiful beaches, alluring Mayan ruins, and delectable seafood. But a trip to the Yucatán is incomplete without exploring the region’s cenotes, which are sinkhole caves, many of which contain swimmable turquoise watering holes. The cenote pictured here is part of the Sistema Sac Actun, which holds the distinction of being the longest surveyed underwater cave system in the world.
In 2008 divers in the Sistema Sac Actun came across the remains of a mastodon, which went extinct about 10,000 years ago, and the bones of a teenaged girl who lived 12–13,000 years ago.
Multi-Course Cave
While most caves are known for one particular speleothemic feature, Lebanon’s Jeita Grotto offers a full buffet of caving treats. The nearly 6-mile system is the longest in the Middle East. It’s accessible only by boat, and features a subterranean river, an underground waterfall, two types of limestone, and a 27-foot stalactite. Though Lebanon is blessed with stunning mountains and coastlines, Jeita Grotto is nonetheless the small, troubled nation’s most recognized natural attraction.
Jeita Grotto was historically a local economic engine, welcoming hundreds of thousands of tourists annually from all over the world. This revenue became yet another casualty of COVID-19, further beleaguering the Lebanese economic crisis.
Size Does Matter
With over 420 miles of surveyed passageways, Mammoth Cave puts other caverns to shame in terms of its sheer mass; it extends to nearly twice the length of the silver medal finisher in this contest, the Sistema Sac Actun underwater cave in the Yucatán, Mexico. Though best known for its sheer mass, the cave is full of a number of interesting curios as well: Fans of architecture from the Middle Ages may be interested in the cave’s ‘Gothic Avenue’, so named because some of its formations resemble Gothic buildings.
Ancient mammoth bones have been discovered in many a cave worldwide, but in this particular instance the name ‘Mammoth’ refers to the cave’s impressive size, not its paleontological contents.
Easy Does the Descent
Majlis al Jinn is another spectacular pit cave (a cave accessed through vertical entry shafts), this time located in the coastal Arabian Peninsula nation of Oman. Though not the most accessible of caves for tourists, those who do get to the cave are rewarded with a temporary respite from the sweltering Arabian heat. Temperatures inside the cave stay between 62 to 64 degrees. Mind you, average daily temperatures in the Omani capital of Muscat climb to 104 degrees in June.
‘Majlis al Jinn’ means ‘Meeting Place of the Genie’ in Arabic. Per local legend, a genie is responsible for creating the three openings to the cave, after lightning bolts that he threw went awry and pierced the earth.
Barbadian Beauty
If while visiting Barbados you ever tire of relaxing on pristine beaches and gorging on flying fish, you can hop over for a look at Harrison’s Cave in the island nation’s highlands. High-calcium water erosion contributes to the cave’s particularly memorable stalagmites, including a set in which one stalagmites appears to be proposing matrimony to the other. So if you’ve been looking for a place to declare your love to your partner, look no further.
The cave is particularly well suited to those with mobility limitations, as its tours are navigated via tram, though the tram does stop and allow visitors to get a closer look at cave highlights.
How Huge Is This?
While some otherwise adventurous types might avoid caves for fear of claustrophobia, they have nothing to worry about in New Mexico’s Carlsbad Caverns: Its limestone chamber, appropriately referred to as ‘The Big Room’, measures 4,000 x 625 x 255 feet. Carlsbad Caverns is the most famous, and the most tourist-oriented, of this National Park’s 119 caves. Some of the Park’s other impressive caverns, like Lechuguilla Cave, are unfortunately open only for scientific researchers.
The Guadalupe Mountains, which make up the exterior landscape surrounding the Caverns, are as picturesque as the Caverns’ interior, particularly at sunset.
Rugged Rainforest
While rainforests are typically thought of as having four levels—emergent, canopy, understory, and undergrowth—the tropical rainforest in Malaysia’s Gunung Mulu National Park is well known for a fifth level, made up of its subterranean caves. The caves contribute to the park’s astounding fauna, as they shelter swallows, swiftlets, and millions (literally) of bats spanning twenty eight species. Travelers can time their visits to the cave to coincide with the dramatic flight formations of the birds entering the caves in the morning, or the exodus of bats at dusk.
Though many of the rainforest’s numerous caves were first surveyed only within the last 25 years, they were originally formed as a result of tectonic uplift several million years ago.