UFO sightings can happen anywhere, and the phenomenon seems especially drawn to the world’s most remote and rugged terrain. In fact, the 10 caves mountains featured here have become legendary gathering spots for lights that dance, crafts that vanish, and legends that whisper of extraterrestrials. Whether you’re a skeptic or a believer, these peaks and their hidden chambers provide a perfect stage for the unexplained.

10. The ‘Hidden People’ Of Snaefellsjokull

The Huldufolk, or “Hidden People,” have haunted Icelandic folklore for centuries, long before the modern UFO craze took off. Some UFO researchers argue that these ancient tales could actually be early accounts of alien encounters, and the Snaefellsjokull glacier itself is widely regarded as a prime UFO hotspot.

According to the legends, the Huldufolk appear humanoid yet possess an elf‑like aura. Enthusiasts sometimes equate them with the classic grey aliens, suggesting that the mountains they inhabit might be concealed alien bases. Whether you view them as mythic sprites or extraterrestrial visitors, the stories remain deeply embedded in Icelandic culture.

Respect for the Hidden People runs deep: locals leave food and gifts at the mountain’s base, and construction projects are occasionally rerouted to avoid disturbing their alleged territory. Even modern infrastructure bows to the ancient belief that the Huldufolk deserve reverence.

9. Glastenbury Mountain

The Bennington Triangle, centered around Glastenbury Mountain in Vermont, has been plagued by eerie disappearances for generations. Between 1945 and 1950, six individuals vanished without a trace, fueling speculation about alien abductions.

Local UFO investigators point to the persistent sightings of strange, hovering lights as circumstantial evidence supporting the abduction theory. The narrative gains further intrigue when Native American lore describes a cursed stone that swallows anyone who steps upon it—some suggest this could be a metaphor for a hovering, stone‑like craft.

Adding another layer of mystery, the region is also known for Bigfoot sightings. Researchers note that many UFO hotspots overlap with reported Bigfoot activity, prompting theories that the two phenomena might be interconnected.

Whether it’s alien technology, a cursed relic, or something else entirely, Glastenbury Mountain continues to be a magnet for the unexplained.

8. ‘Upside Down’ Mountain

Overlooking the tiny French village of Bugarach, Pic de Bugarach earned the nickname “Upside Down Mountain” because its upper geological layers are older than those beneath them—a reversal that suggests a massive ancient upheaval.

UFO enthusiasts and ancient‑astronaut theorists argue that this geological oddity could be the result of an intentional alien explosion, with the flat summit serving as a possible landing pad for spacecraft of an older civilization.

In the lead‑up to the 2012 doomsday predictions, the mountain attracted a wave of UFO researchers and apocalyptic believers who bought nearby land, hoping to be present when the world supposedly ended. While the apocalypse never arrived, reports of strange lights and rumors of hidden alien bases within the mountain’s cavernous network persist.

7. Alien Ship In The Cave Systems Of Antarctica

Antarctica, a continent already steeped in mystery, became the focus of another UFO claim in January 2017 when enthusiasts posted photos of what appeared to be a classic flying saucer jutting from an ancient ice‑bound cave mouth.

Social media erupted with theories ranging from a crashed extraterrestrial craft to the remains of a secret Nazi UFO project. Some observers argued that the half‑visible saucer suggested a crash‑landing, while others believed it was evidence of a concealed alien outpost.

The sighting coincided with other recent claims of pyramid‑shaped structures spotted via Google Earth, as well as reports of hidden entrances to alleged inner‑Earth bases. Whether these images are hoaxes, misinterpretations, or genuine anomalies remains a hot topic among conspiracy circles.

6. Alien Base At Mount Adams

During the summer of 2017, attendees of the Enlightened Contact with Extraterrestrial Intelligence (ECETI) conference in Washington reported spotting a massive opening near the summit of Mt. Adams, which many interpreted as a portal to an alien base hidden within the dormant volcano.

The mountain’s UFO history stretches back to 1947, when the Keith Arnold incident recorded nine high‑speed crafts that vanished as they approached Mt. Adams. This earlier encounter lends some weight to the 2017 claims, suggesting the volcano may indeed house a fleet of extraterrestrial vessels.

5. The Ominous Slabs Of Black Mountain

Formed over 200 million years ago from solidified magma, Black Mountain in Queensland is a jagged landscape of massive granite blocks that locals call Kalkajaka, or “Mountain of Death.” Aboriginal lore holds that malevolent spirits inhabit the stone, preying on anyone who ventures too close.

Witnesses have reported seeing humanoid beings that match classic reptilian descriptions popular in UFO and conspiracy circles. Pilots flying overhead have encountered bizarre phenomena, including unexplained lights and sudden navigation failures, adding a technological mystery to the spiritual one.

Even more unsettling, numerous people have reportedly vanished without a trace around the mountain. Those who attribute these disappearances to UFO activity claim the lights signal alien abductions, turning Black Mountain into a chilling nexus of both myth and extraterrestrial speculation.

4. What Lurks In The Caves Of Mount Shasta?

Mount Shasta dominates the Northern California skyline and, according to indigenous narratives, serves as the planet’s creation point. In modern times, the mountain has become a hotspot for UFO sightings, with video evidence of strange craft disappearing into what witnesses describe as a portal above the peak.

Equally intriguing are reports of red‑eyed, luminous creatures roaming the extensive cave systems at the mountain’s base. One recent account involves a three‑year‑old boy who vanished for five hours while camping; he later claimed a “robot Grandma” escorted him into a cavern filled with guns and spiders, insisting that alien beings had placed him back into his mother’s womb.

While skeptics might attribute the boy’s tale to a traumatic imagination, others point to the grandmother’s own experience—spider‑like bite marks on her neck and vivid dreams of being watched by a red‑eyed entity—suggesting a possible link between the cave dwellers and the alleged extraterrestrial presence.

3. The ‘Thought Transfer’ Base At Mount Hayes

Remote‑viewer Pat Price asserted that deep within the core of Alaska’s Mount Hayes lies an alien installation whose primary purpose is “thought transfer,” a technique allegedly designed to manipulate humanity’s collective consciousness. According to Price, the extraterrestrials masquerade as ordinary humans, moving unnoticed among us.

Price’s conclusions stem from remote viewing—a controversial method that has left many UFO researchers skeptical. Nonetheless, the region is riddled with UFO reports, and pilots have documented odd anomalies in their navigation equipment when flying near Mount Hayes.

The frequency of these incidents was so pronounced that, during the 1950s, the FBI launched an extensive investigation to determine the cause of the strange readings, further cementing Mount Hayes’s reputation as a potential extraterrestrial hub.

2. The Broad Haven Triangle Of The Welsh Mountains

Wales boasts several UFO‑active zones, but perhaps none is as renowned as the Broad Haven Triangle, a rugged valley in the southwest that has attracted consistent sightings for decades.

In 1977, a wave of reports flooded the area, prompting the UK Ministry of Defence to launch a covert investigation. The findings remained classified for years, underscoring the gravity of the phenomenon.

The most iconic incident involved a group of schoolchildren who observed a disc‑shaped craft landing in a field near their school. A humanoid figure emerged, lingered for several minutes, then re‑entered the craft, which subsequently vanished into the surrounding woods, heading toward the Welsh highlands.

1. The Superstition Mountains

The Superstition Mountains in Arizona, a popular hiking destination, have also become infamous among UFO circles for alleged encounters with reptilian humanoids who allegedly abduct hikers and transport them to a concealed underground base.

One harrowing testimony comes from a woman known only as “Angie.” While traversing the valleys, she was startled by a masked figure that, upon closer inspection, revealed a reptilian face. The encounter caused her to black out, and she later awoke behind the wheel of her car, driving home with no recollection of the intervening moments.

Through hypnotic regression, Angie recalled being taken to a cavern deep within the mountains, surrounded by several reptilian beings. She described being restrained on a table, naked, as one of the creatures approached her. Although she could not recall the exact outcome, she believes she was assaulted before being returned to her vehicle.

Why These 10 Caves Mountains Are UFO Hotspots

From Iceland’s icy glaciers to Arizona’s sun‑baked valleys, each of these ten caves mountains combines striking geology with folklore, mysterious disappearances, and a steady stream of anomalous aerial phenomena. Whether you view them as genuine alien outposts, sites of cultural myth, or simply places where the human imagination runs wild, they remain some of the most compelling locations on Earth for anyone chasing the unknown.

Caves are perhaps one of the most unexplored and inhospitable environments found on Earth. Despite this apparent inaccessibility, however, explorers and adventurers continue to seek and find entirely new subterranean worlds around the world. Some of the most fascinating caves we know of are also unique, thriving ecosystems, housing a number of species with adaptations not found anywhere else on Earth.

Explore the 10 Fascinating Caves

10 Marble Caves, Patagonia

Estimated to be over 6,000 years old, the Marble Caves sit on the Chilean side of General Carrera Lake in Patagonia. Over countless millennia, the lake’s turquoise waters, rich with calcium carbonate washed down from nearby glaciers, have slowly dissolved and carved the underlying limestone, sculpting the dazzling marble‑like formations that grace the shoreline today.

Beyond their striking marble appearance, the lake’s vivid blue hue—produced by suspended particles that reflect sunlight—gives the whole scene an almost alien quality, drawing adventurers from across the globe. Reaching the caves remains weather‑dependent, as the rugged terrain and choppy waters of General Carrera Lake can make access tricky.

9 Cave Of The Crystals, Mexico

The Cueva de los Cristales, better known as the Cave of the Crystals, was uncovered in 2000 beneath the Sierra de Naica mountain in Chihuahua, Mexico. A serendipitous find during a routine mining dig revealed colossal gypsum crystals, some stretching nearly 40 feet, giving the cavern an otherworldly, alien feel.

Scientists later learned that these crystals formed through hydrothermal mineralization—a process where volcanic heat dissolved minerals that later precipitated as massive gypsum structures over tens of thousands of years. Unfortunately, the cave’s extreme temperature and humidity make regular visitation a challenge for casual tourists.

8 Ajanta Caves, India

Ajanta Caves, a UNESCO World Heritage site, showcase a series of rock‑cut Buddhist monasteries and temples. Nestled in the Aurangabad district of Maharashtra, these caves were hewn between the 1st century BC and the 7th century AD, and are celebrated for their vivid frescoes that adorn walls and ceilings.

Carved from volcanic rock within a horseshoe‑shaped gorge, the complex comprises 30 individual sanctuaries and monasteries. Their construction unfolded in two distinct phases: the early Satavahana period (2nd century BC to 1st century AD) and a later Vakataka era (5th to 6th centuries AD), each leaving its own architectural imprint.

7 Waitomo Glowworm Caves, New Zealand

Formed over more than 30 million years, the Waitomo Glowworm Caves are famed for their bioluminescent residents, especially the native Arachnocampa luminosa. These tiny glowworms line the ceiling, creating a star‑filled spectacle that dazzles visitors.

The caves were first charted by Maori chief Tane Tinorau and British surveyor Fred Mace. Today, guided boat tours glide along an underground river, allowing guests to drift beneath a ceiling glittering with thousands of glowworms, evoking a magical night‑sky experience.

6 Eisriesenwelt, Austria

Dubbed the world’s largest ice cave, Eisriesenwelt—German for “World of the Ice Giants”—draws tourists to Salzburg’s alpine region. Spanning more than 26 miles, its origins date back at least 100 million years, making it a geological marvel.

The cavern owes its existence to a blend of water erosion and tectonic activity. While only the front section welcomes the public, the remaining 25 miles of icy passages stay off‑limits, preserved by perpetual cold winds that keep the accessible chambers frozen year‑round.

5 Kamchatka Ice Cave, Russia

The Kamchatka Ice Cave resides on the remote Kamchatka Peninsula in far‑eastern Russia. Its formation stems from the freeze‑thaw cycles of massive glaciers, carving a sub‑glacial tunnel about 0.6 miles long that weaves deep beneath the ice.

Dynamic glacial movement and frigid temperatures have sculpted this icy chamber, while nearby volcanic activity occasionally melts sections of the roof, casting an eerie, luminous glow inside the cavern.

Beyond the ice cave, Kamchatka boasts volcanoes, geysers, grasslands, and snow‑capped peaks. Summer offers milder weather, making it the optimal season for explorers aiming to venture into these rugged wonders.

4 Blue Grotto, Italy

The Blue Grotto, or Grotta Azzurra, is a sea cave perched on Capri’s northern coast in Italy. Relentless erosion by the Tyrrhenian Sea sculpted this hidden gem, which now serves as a rare but popular attraction on the upscale island.

Visitors reach the grotto via small boats that thread through a narrow entrance. Inside, the cavern stretches roughly 200 feet in length, 80 feet wide, and plunges 490 feet deep. Archaeological studies reveal Roman-era sculptures, confirming that Emperor Tiberius once used the grotto as a private swimming pool.

3 Sistema Sac Aktun, Mexico

Spanning over 200 miles in length and reaching depths beyond 390 feet, the Sistema Sac Aktun stands as Earth’s longest underwater cave system. Located along the Caribbean coast of the Yucatán Peninsula, it forms part of an extensive network of submerged passages.

Since 1987, divers and researchers have charted more than 220 cenotes—sinkholes created when cave ceilings collapse—within the system. Known as the “white cave,” Sac Aktun boasts a diverse array of flora and fauna thriving in its multiple underwater ecosystems.

2 Mammoth Cave System, USA

Nestled in Kentucky’s Mammoth Cave National Park, the Mammoth Cave System stretches roughly 350 miles, earning its title as the world’s longest known cave network. Vast chambers and hidden passages continue to be explored, revealing new wonders beneath the surface.

Formed over millions of years as limestone dissolved under the pressure of underground rivers, the cave showcases an intricate maze of tunnels, stalactites, and stalagmites that dazzle visitors. Evidence shows Native American peoples utilized and explored these caverns long before modern discovery.

Recognized for its cultural and natural importance, the Mammoth Cave System holds UNESCO World Heritage status, protecting both its geological marvels and the endangered species that call it home.

1 Son Doong, Vietnam

Son Doong, perched in Quảng Bình province of central Vietnam, towers at about 650 feet tall and spans roughly 500 feet wide, making it the largest known cave on Earth by volume. Though discovered in 1990 by local Ho Khanh, full scientific exploration didn’t occur until 2009, unveiling just a fraction of an immense system—about 70 % of which remains untouched.

Millions of years of limestone erosion birthed this colossal cavern. Its sheer size demands a vertical ascent or descent of at least 280 feet to enter or exit, underscoring the challenge and awe of exploring this subterranean giant.

Many caverns are known for their crystal pools, majestic rock formations, winding corridors, and enchanting “rooms.” Millions of men, women, and children throughout the world tour such caves, admiring and learning about the hidden wonders of these subterranean worlds. However, not all caverns are used to showcase such marvels or educate the public.

The ones on this list were, at one time or another, used for unusual and sometimes bizarre things that go beyond simple exploration. So let’s go deep and discover all the possibilities you can choose from the next time you find yourself in a cave.

Related: 10 True Horror Stories Of People Trapped In Caves

10 Dancing, Cockfights, and Moonshining

The Lost Sea, the largest underground body of water in the United States, is near Sweetwater, Tennessee, in Craighead Caverns, but this feature is not the only one that the caverns offered in times past.

According to the history of this extensive cave system, the decision in 1915 to open the caverns to the public resulted in the installation of a dance floor in one of the system’s large upper rooms. Musical and theatrical presentations were also performed. For those who sought to slake their thirst for blood, cockfights were also a regular feature of underground entertainment. In addition, the caves were the site of liquor stills in which bootleggers distilled white lightning.^[1]

9 Ku Klux Klan Meeting Place, Speakeasy, and Concert Hall

The Fantastic Caverns in Missouri’s Ozark Mountains, which today feature a “drive-through” attraction operated by the Trimble family, owners of the Shepherd of the Hills Outdoor Theatre in Branson, were once put to a much worse use.

After a dozen members of the Springfield Women’s Athletic Club explored the caves in 1867, at the invitation of the owner, John Knox, no one else entered the caverns until the Ku Klux Klan (KKK) began holding meetings in the Grand Ballroom, as one of the cavern’s chambers was known. Fortunately, the period during which the white supremacist hate group occasionally occupied the caves was brief.

Several years after police finally shut down the operation, the caverns were put to another use. The tenancy of the speakeasy that operated in Fantastic Caverns shortly after Prohibition outlawed the importation and the brewing or distillation of alcoholic beverages as well as their possession, storage, transportation, sale, or consumption was of a longer duration than the period of the KKK’s meetings. In addition to serving mixed drinks, the underground speakeasy offered patrons “gambling and all sorts of carousing.”

After the police closed the speakeasy, another commercial use was found for Fantastic Caverns when, during the 1950s, a country music show, Farm-A-Rama, was taped in the auditorium room. Like the seedier operations that had called Fantastic Caverns their home, however temporarily, the Farm-A-Rama show’s use of the caves didn’t last long, despite appearances by such celebrated country music stars as Tom T. Hall and Buck Owens.^[]

8 Underground Railroad Shelter

As the U.S. Department of Agriculture website notes, Sand Cave in Illinois, west of Crow Knob and north of the Miller Grove Community, was a stopping point on the Underground Railroad, offering shelter and protection to runaway slaves seeking to escape to the north. The cave was well-concealed among the area’s dense forest and rugged terrain. Sand Cave may not have been the only such sanctuary in the region since such spots as Ox-Lot, Brasher Cave, and Fat Man’s Squeeze offered other places to lie low for a while without the likelihood of being found.^[3]

7 Playhouse

In July 2013, Samuel Beckett’s play Not I was performed in the underground theater in the Marble Arch Caves in Northern Ireland. The Happy Days Enniskillen International Beckett Festival has become renowned for its site-specific events, one of which featured cantos read aloud by reporter Jessica Campbell and others following the presentation of Beckett’s play.

Campbell describes Clara Simpson’s performance of Not I as powerful and meticulous: “With only her mouth visible by spotlight in the darkness, she performed the fast-paced Beckett play without any flaws, firstly in English, and then in French, leaving the audience in awe of her talent and contemplating what was to come next.”

Next came the audience’s departure by boat as they “began their journey through Hell,” amid the babble of the voices of the lost, as Campbell added her own reading of Danté’s dark words describing the horrors of Hell. The theatrical group took pity on the audience, though, as opera singer Ruby Philogene began her “angelic rendition of Dido’s ‘Lament,’” lifting the darkness and replacing it with hope before she physically led the audience from the depths of Hell to the light of the natural world above, singing “Amazing Grace.”^[4]

6 Concert Hall

The Arwah Cave at Sohra, Meghalaya, India, became a concert hall on July 16, 2022, when a musical took center stage, with musicians percussion and string instruments and vocalists belting out songs. The production, “KI Sur Na Pubon,” translates as “message from the cave.”

Clean Sohra Campaign leader Alan West Kharkongor explained that the message relates to assuming the responsibility of protecting and preserving mother nature, whether nature is represented by “the cave, the streams, [or] the waterfalls.” At the same time, a folk-fusion band, Kit Shangpliang of Summersalt, which performed in the show, saw the event as an opportunity to promote young musicians as the event showcased one of Meghalaya’s “scenic natural assets.”^[5]

5 Rehearsal for Extraterrestrial Exploration

As reporter Paul Rudder notes, NASA personnel believe that extraterrestrial caves, such as those found on Mars, are one of the best places to look for life since such environments offer natural “protection from cosmic rays and extreme temperature fluctuations.”

NASA already has the robots on hand that are needed to conduct such searches, but the robots must be tested and perfected before they are deployed in extraterrestrial caverns. Fortunately, Earth provides Mars-like caves that NASA’s Project Braille can use to accomplish this purpose.

The artificial intelligence known as NeBula will allow the robots to process data and make decisions independently of human input, but the “brain” will require special protection from temperatures and radiation. SPOT, a Boston Dynamics automaton that the company describes as “an agile, mobile robot that navigates terrain with unprecedented mobility,” will provide such protections. It also responds well to NeBula’s high-level decisions and commands.

Not only is SPOT equipped with wheels, but it is also able to walk, an ability that will allow it to traverse uneven terrain without the benefit of roads and flat surfaces. Such capabilities are essential since “robots won’t be able to communicate with scientists once they are inside the caves.” SPOT can also see, hear, and think robotically while also carrying the necessary amount of scientific equipment and keeping up a “reasonable amount of stability, speed and endurance while it navigates another world.”

The rehearsal for extraterrestrial exploration represented by SPOT’s investigations of Earth’s caverns should also help NASA to reach another goal: the creation of robots that can perform missions with complete autonomy.^[6]

4 Therapy

The rich rock salt deposits of Salt Healing Cavern Berchtesgaden in Germany’s Bavarian Alps benefit visitors’ health. According to the cavern’s operations manager Jan Freiherr von Werthern, the site allows people to immerse themselves in the energy of millions of tons of natural salt from the original ocean 250 million years ago, thus alleviating stress while promoting deep relaxation.

During a three-week stay featuring two hours inside the cave daily, visitors say they experience “improvements in a range of conditions including hay fever, depression, asthma, bronchitis, rheumatism, allergies, and sleeplessness.” Part of the treatment seems to involve a sort of meditation during which guests take note of salt vein patterns while they let energy sink in.

Of course, such therapy has yet to be “universally accepted as a complementary treatment by the medical industry.” If anecdotal evidence is any indication of the effects of such alleged therapy, it worked for an elderly man who said the treatment made him feel as if he had had his “batteries fully recharged” and left him feeling relaxed, revitalized, healthier, and refreshed.^[7]

3 Funerary Rites

During the Ice Age, Britons ate each other, writes Lisa Hendry in her online article for the Natural History Museum in London.

No, they weren’t starving. They had, however, become adept at butchering and carving human remains, says museum scientist Dr. Sylvia Bellows. The discovery of a group of remains in Gough’s Cave in Cheddar, Somerset, England, indicated that the bones of a teenager and a young child had been chewed by others. The children’s long bones, like their ribs, had been cracked open and gnawed, the better to “extract marrow and grease.” Skulls had also been shaped into drinking vessels and bowls.

According to the article, the dead were Magdalenians, a cultural group of Cro-Magnon hunter-gatherers from southwest Europe who had likely immigrated from Belgium and the Netherlands about 15,000 years ago, when Britain and central Europe were still linked by a land bridge. Warmer weather—the climate had begun to warm up—may have motivated their migration.

What led to cannibalism? The cause was not a lack of food; there was an apparent abundance of animal meat. The transformation of skulls into cups and bowls, a painstaking process, suggests a possible symbolic meaning related to a ritual. And the cannibalism itself, like the engravings found on the bones, “may have been a way of remembering the deceased’s life or death.”^[8]

2 Air Raid Shelter, Ballroom, and Music Venue

The St. Clements Caves in West Hill in Hastings, East Sussex, England, were formed in part by nature and in part as the result of sand mining. Although rumor has it that the caves were used by smugglers, no evidence supports this claim. The fact is that the caves were used as a hospital, the Historical Hastings website states, adding that the caves were also used as an air raid shelter and, later, as a ballroom/music venue.

During World War II, the caves, which could accommodate 900 people, did double duty as an air raid shelter and a repository for the safe storage of archive material.” As Diana Tanner recalls her family taking year-long nightly refuge in the caves during the war, the makeshift air raid shelters were equipped with triple-decker bunk beds so narrow that her mother tied Diana and the rest of the family in place to prevent them from falling off the beds in their sleep. Most mornings, the family awakened covered in a fine coating of damp sand.

Like everyone else, her mother, Diana remembers, panicked when a bomb fell nearby, the concussion of its blast shaking the area. Fearing that she and her loved ones might be buried alive should another near-miss befall them, she called an end to them taking nightly refuge in the caves.

After the war, the caves were put to other uses, with the Rolling Stones and other bands performing in the shelter-become-a-ballroom. Dinners, other functions, as well as tours of the caves were also featured. The website’s photographs depict both the horror of war (children participating in a “gas mask drill” inside the caves in 1941) and happier later pastimes, such as concerts and guests lining up for a tour of the caves.^[9]

1 Film Location

Many films, in a variety of genres, have been shot inside caverns, including the horror movie The Descent (2005), the historical drama A Passage to India (1984), the action-thriller Sanctum (2011), and the science fiction film Journey to the Center of the Earth (2008), to name but a few. Something about the close confines of dark, winding caverns and the possible presence of bats, or even monsters, seems to make such locations intriguing to filmmakers across the storytelling spectrum.

One of the most recent movies to have been filmed in such a location is Thirteen Lives (2022), directed by Ron Howard and starring Viggo Mortensen, Colin Farrell, and Joel Edgerton. The movie is based on the 2018 rescue by Thai officials, experts, and Navy SEALs of the twelve members of a football team and their coach, who were trapped for eighteen days inside the Tham Luang Nang Non cave in northern Thailand. The cinematography brings the harrowing ordeal of the thirteen trapped spelunkers alive so that audiences can themselves experience the claustrophobic tight spaces of the narrow, water-filled corridors of the Tham Luang cave network.

Filming the movie was terrifying, Farrell revealed in an interview with Entertainment Tonight. Recalling the configuration of the set, an “impressive network of caves based on the topography of the caverns and filled with water,” Farrell, who admitted that he is not the best swimmer, found shooting scary. He noted, “once [the cast and crew] had descended into the artificial caves, there was no way up.”

Adding to the fright, the underwater scenes were filmed indoors in the dark, making it impossible for Farrell to get his bearings. “There’s a lot to be said for being able to look up in water and see the surface,” Farrell explained. “So when you can’t, and there’s actually a ceiling over your head, and there’s no air at all, it just wreaks havoc on my mind.” Fortunately, the movie’s cast and crew, like the coach and his football team, survived their respective ordeals.^[10]