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The Lost Forest World of the World’s Largest Cave

In this technologically advanced age of Google Earth and ever expanding exploration of our planet, there are fewer and fewer places that remain hidden from the gaze of humankind. We are exploring the forests, mountains, and seas of the world at an ever growing pace, and the ancient places that once lied in pristine remoteness beyond our grasp are being uncovered for all to see. But what of under our feet? What of the lost realms of the deep places of the world? In the case on one massive cave in Vietnam, a lost, prehistoric world sat hidden for millions of years deep under the forest floor until pure happenstance started our first steps into a place that time forgot.

In 1991, a local farmer by the name of Ho Khanh was walking along a stretch of lush forest within the heart of the Phong Nha Ke Bang National Park in Quang Binh province, near the border between Laos and Vietnam. It was an area that he had passed many times before and he was not paying any particular attention to his surroundings when suddenly the jungle floor opened up beneath him and Mr. Khanh only barely managed to hold on as the ground crumbled beneath him. When he was able to get his bearings, he peered into the gaping chasm that had suddenly appeared out of the thick foliage and saw that there was now a steep drop where he had stood that descended down into darkness. By pure chance and blind luck, this man had discovered an entrance that had remained hidden from man for millions of years into what would turn out to be the largest cave in the world, a behemoth five times larger than the largest known cave at the time.

World's largest cave.

World’s largest cave.

For years the entrance remained unexplored. Locals were afraid to go near it, partly because of the dauntingly steep drop, and partly because of the strange roaring sounds that bellowed out from its depths, later found to be caused by a raging river far below. In addition, there was an eerie mist that seeped out of the cave, a phenomenon caused by the cooler air below meeting the hot jungle air above, which gave the area a surreal, unearthly atmosphere. All of these things conspired to deter the superstitious locals from entering, and so the cave mouth remained unexplored and untouched, just as it had been for countless millennia.

It was not until 2009 that members of the British Cave Research Association undertook an expedition to penetrate into the mysterious jungle cavern and explore the darkness below. By that time the man who originally had found it no longer even remembered exactly where it was, so the team had to ascertain its position from what he could recall and from other locals, who still feared it. It was to be the beginning of a breathtaking journey into an ancient, forgotten realm that no human being had ever set foot in.

Son Doong Cave

Son Doong Cave

The expedition, led by Howard and Deb Limbert, began their descent in April of 2009. The first thing that became quickly apparent was the sheer, enormous scale of the place. Using ropes and harnesses, the team rappelled down a 260 foot vertical drop before they finally reached the bottom, where the thick, absolute silence of the place was said to be almost deafening. An investigation of the surroundings showed that the cave was largely formed of limestone, which had been eroded from under the Annamite Mountains of Vietnam between 2 to 5 million years ago. Upon reaching the bottom, the team did not get far before they came up against a 200 foot wall of muddy calcite, which they called “The Great Wall of Vietnam,” that prevented any further progress.

In 2010, the frustrated team was finally able to traverse the enormous wall and continue their journey. What they found within thoroughly amazed all present; an alien world the likes of which none of the experienced cavers had ever seen. The cave, now known as Son Doong Cave, or “the cave of the mountain river” was far larger than anyone had ever imagined. The largest cavern stretched for over 5 km (about 3 miles), was 650 feet wide, and had walls that soared upwards over 200 m (656 feet), high enough to comfortably fit a modern day skyscraper.

Son Doong Cave. That little speck with the light is a person.

Son Doong Cave. That little speck with the light is a person.

Jutting from this immense cavern were stalagmites and stalactites that were up to 80 meters (265 ft) long, some of the largest in the world. Along the Great Wall of Vietnam were scattered abnormally huge “cave pearls” as big as baseballs, which are formed when dripping water forms layers of calcite around grains of sand over hundreds of years. There were also various rimstone pools dotting the cavern and even a lake. Throughout this mystical landscape meandered a river that ran the length of the cavern and disappeared into the unknown darkness of other caves that branched off from the main one. In all, it was found that the main cavern branched out into a network of over 150 individual, interconnected caves.

The biggest surprise to be found here was a massive forest growing undisturbed deep in the heart of the cavern among the stalagmites and stalactites, a feature not normally associated with the subterranean recesses of caves. Sections of the cavern’s ceiling had eroded away over millennia and collapsed, becoming gigantic windows that allowed columns of sunlight to penetrate into the darkness, illuminating a huge section of the cave and allowing ancient trees up to 30 m high (100 feet) to thrive here. This lush vegetation that blanketed the cave floor thrummed with life, hosting a plethora of wildlife from the outside world, including insects, rare birds such as the chestnut-necklaced partridge and the short-tailed scimitar babbler, snakes, lizards, monkeys, bats, flying foxes, and numerous species of butterfly, as well as an unknown number of as yet undiscovered new species.

The Jungle of Son Doong cave.

Approaching the jungle of Son Doong cave. Again, those little red specks along the bottom are people.

Currently, Son Doong cave is recognized as being the world’s largest cave by far, much larger than the previous title holder, Malaysia’s Deer Cave. The main cavern is so large that it has its own climate, and clouds have even been known to form within it. It is massive enough to house an entire city block, high enough to hold 40 story high skyscrapers, and those who have been here describe being truly humbled by the sheer scale of this place.

The lost world of Son Doong cave still has its mysteries, and much of the cave system remains unexplored. Perhaps one of the most exciting areas of further exploration lies in the prospect of finding new species of plants and animals here. The animals of the cave can generally be categorized into two types; those that live in the forested area and those that dwell in the inky black recesses of the enclosed areas. Already several new species have been discovered here, including several species of plant and insect, as well as a new type of gecko, a tree frog, and a striped hare. Since only a very few expeditions have attempted to catalog species within the cave, there are undoubtedly more to be found. There have been several species that have been spotted that have not been identified as of yet, including a possibly new type of monkey, and mysterious creatures have been seen skittering through cave passages and even swimming through the river and lake here. One of the only scientists to have studied the dark interior passages of the cave, German biologist Anette Becher, described spotting a myriad of as yet unknown fish, insects, and millipedes within the gloom, many of them albino and sightless. It seems that we are only beginning to scratch the surface of the biodiversity that may lie here waiting to be discovered.

Part of Son Doong's forest

Part of Son Doong’s forest

Other mysteries of Son Doong cave include the source of the underground river that runs through the cave and an only recently discovered side cave that is full of rare and undescribed fossils, many of them very large and some of them dated as being around 300 million years old. The original team to explore Son Doong has plans to launch another extensive expedition in order to further investigate the many mysteries of the caves.

In 2013, the first steps towards opening the lost world of Son Doong began when the tour company Oxalis began offering adventurous souls the chance to spend several days camping and exploring within the cave’s massive interior. The first expeditions are pilot tours, with the company planning to expand the tours in the future. The excursions are not for the faint of heart. In order to reach the cave, one must trek through remote jungle wilderness to the entrance of the cave, upon which a several hundred foot sheer vertical drop awaits. Only after after rappelling down the perilous face of the cliff will one finally be able to look upon this vast, mysterious world. Those who have seen the cave say that the sheer scale of the it is hard to comprehend without seeing it in person, and that it is difficult to describe in words how humbling and awe inspiring the experience is.

Rappelling into Son Doong

Rappelling into Son Doong

With tours such as this underway and yet more to be planned, it seems that just as with other lost and hidden places of the world, the caves of Son Doong too will have there mysteries slowly peeled away for all to see. For now, though, it is still a place of wonder and awe, and is still largely unexplored. What lies here awaiting to be discovered in the gargantuan cave’s many dark passages and within the ancient trees of  its misty, sun pierced subterranean forests? There is much left to learn about this vast, lost cave world, and much exploration left to do before we even begin to fully understand this fascinating natural wonder. Son Doong has not given up all of its mysteries just yet.

The discovery of Son Doong also poses another question. What other lost places remain out there for us to find? It is exciting to think that right here on our own planet there may be whole new vast, alien realms, even new ecosystems, hidden away from us, waiting to be discovered. Or perhaps maybe they will never be discovered, and will remain untouched by human hands as they have for millions of years and will for millions more. Whatever the case may be, even as the modern world seems to become ever smaller, it appears that there are still surprises locked away within this planet of ours.

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  • Craig Campbell

    Great article Brent! Do you have any articles on “AUSTRALIA”?

  • Craig Campbell

    Great article Brent! It wasn’t so long ago that “glow worms” were hidden from the gaze of humankind too!

  • Brent Swancer

    Thanks! No articles on Australia yet, not that there isn’t plenty of stuff to write about over there! I’ll get on it!

  • Most of the worlds groundwater is NOT of surface and recharge zone origins, but is ELEMENTAL WATER, a byproduct of Earth’s fission elemental atoms and fission heat breakdown of mantle compounds. See “Earth’s Missing Geothermal Flux” for more on this array of fission byproducts including Abiogenic oil, inert gases and even atmospheric gases, posted at the FSS site.

  • marshall tackitt

    WOW! I absolutely LOVE to hear that we are still discovering wonderful, magical places on our small blue marble! Let us all hope and pray they don’t destroy it.

  • Junius Junius

    By pure chance and blind luck, this man had discovered an entrance that had remained hidden from man for millions of years Was there a date etched into the cave, something like “Cave, built 2 million bc by little people from No China, with parts made in Japan“Or are they just guessing in a wild effort to sound smarter than they average McDonalds manager for the day.

  • mythenjoseph

    Amazing photographs, the humans in the pictures are dwarfed by the sheer size of the cave.

  • BarryBarry

    QuadCopters…Go Pro…Internet.

    No passport needed.

  • Eric Crawford

    Plus all those dinosaurs down there!

  • amuncat


  • Kyara Peacock

    I want to live there!

  • NikL

    It should not be open to the public. It needs to be kept as pristine as possible or it will get ruined. Mount Everest, anyone?

  • Brent Swancer

    Right, Canada too. Any other requests while I’m here?

  • Brent Swancer

    Including me.

  • Simon Finn

    Amazing. Shangri-La really does exist.

  • d12d

    I just fell in love…

  • El Raúl

    I don’t think it’s a good idea to offer tours to this place. It’s a fact people ruin everything; just think about Mount Everest, as NikL said, or the Amazonas, or even my country’s Torres del Paine. Tourism may be wonderful as it helps us visit places we don’t see every day, but it causes a whole lot of destruction and that’s a hell of a high price to pay. This cave should be remain untouched.

  • They should close it off from invading tourist and leave the place to be explored, documented and mapped by scientists for a while, then left alone for the forseable future. This will ensure that the coming generations have something to marvel at.

    Tourism….it will ruin EVERYTHING about this place.

  • skybluskyblue

    “No oil company has ever successfully found a well using the theory and it is generally considered pseudoscience on the order of global warming denialism.” I *knew* you sounded suspicious. Don’t trust this guy.

  • Jana Kelly

    I have read this years ago and I remain in awe .This should humble us to repect this and do not allow man to enter.

  • Wow, this place is truly EPIC!

  • Joyce Godwin Grubbs

    There is still such beauty to be discovered. Happy to have lived to see this.

  • Von Halford

    We need more Venus articles

  • Mount Everest is definitely a horror story, no argument there. I think a lot of that has to do with the extreme remoteness and logistical nightmare of keeping a place like that in good shape when it receives that much traffic.

    However, I think tours can be done right, and it would be a shame to keep this place off limits forever… I was at Mammoth cave recently, and the NPS has done a great job with it. They’ve kept something like 90% of the system off limits, and the rest is tastefully maintained.

  • J. Mie

    This world is way too big to see in one lifetime… this is going on the next life bucket list.

  • John Taggart

    (1st guy) Hey man we just discovered this place that has NEVER been touched by man, EVER! (2nd guy) Wow thats AWESOME! (2nd guy) Lets make a company that charges money to bring people here! (1st guy) Thats a great idea….

  • Phyl

    Wow ! What an amazing thing this is. That we are seeing something truly pristine and untouched by the destructiveness of man, wow!

  • Matty Haxx

    Though I do agree that holding tours of this place has the potential to taint it, I do not assume that tours will be held very often. I also feel that the caliber of patrons to such a tour would be limited to pretty hardcore hikers and spelunkers, of which generally hold such wonders to a high standard.
    Besides, it would be a shame if such a place existed and no one was ever allowed to actually see it 🙂

  • David Moore

    Guyana, sir, Guyana

  • Michelle O’Neal

    To walk in this cave system would truly be an honor! Something that is a wonderously unspoiled area,untouched my man….just amazing! A bucket
    Ist experience for sure!

  • hanna reddigan

    I found more pics of the son doong caves thought this miht interest others here: btw these pics are TRULY amazing!

  • D Brian Hoffman

    Viet Nam is a cash poor country and a “Marvel” such as this will bring tourists willing to spend high cash amounts to explore a huge cave such as this. To believe it possible to have a site such as this “sealed off” for future generations to “Marvel at” is simple in the extreme. Viet Nam will decide what is best for Viet Nam. To expect otherwise is taking a far too unrealistic view of how governments govern.

  • Godsbane777

    My god, how I would love to explore in there.

  • Godsbane777

    Jeezush, all these people seemingly angry it was found. There are benefits to being the spearhead of evolution. Such as being able to go anywhere technology allows…