Largest Cave in World in Terms of Volume

July 2014: I first learned about the great cave when I flipped open a National Geographic magazine and I saw photos of a place that was so huge and incredible that I didn’t think it was possible for normal people to reach it. I figured only scientists with secret special government approvals could visit such a beautiful and wild place in a country like Vietnam. I decided I was going to research the cave and find a way to get in. I was resigned to sneaking in with the help of local indigenous tribes if I had to but, in the end, I was able to enter the cave by joining a weeklong paid expedition trip. The cave was heavily protected by the Vietnamese government and no company was allowed to enter the cave except for one local Vietnamese company that was managed by a British caver, who led one of the first exploratory expeditions into the cave in 2009. The cave, located in a wild reinfested mountainous stretch of land, had been concealed and no one was known to have entered it before the expedition. Since no other companies could enter the cave, this meant that my group of 5-7 tourists and 20-30 porters and guides would have the entire cave complex to ourselves for the week. I was fortunate to sign up for one of the first tourist expeditions into the cave since its opening. This was a cave of my dreams. A place I had been searching for all my life and this is the story of my adventure.



About Son Doong Cave

Location of Cave just south of the old DMZ in Southern Vietnam

Han Soon Dong is located near what was once the demilitarized zone dividing the north and south of Vietnam during the war. The jungle clad mountains surrounding the cave are wild and home to many other caves. These caves served as a sanctuary for the Viet Cong during the war where they would hide out from the relentless ariel assault from American planes. The jungles were and still are also home to wild animals such as Gibbons, and even some elephants and tigers, however I didn’t see any and one of our guides did mention to me that he had seen a tiger but that it has been a few years. Han Soong Don Cave has the largest chamber in the world and is large enough to fly a Boeing 747 through its chamber while allowing plenty of extra space for the plane to fly. A river cuts through the cave and the cave is only accessible in summer months during the dry season because in the rainy season outside of these months, the cave floods with water and is difficult to access.

To enter the cave a permit is needed from the Vietnamese government and only one local operator is certified to bring tourists to the cave. A strict limit is imposed on the number of people that can enter the cave at any one time and there are strict rules in place to protect the cave.


Getting to the Cave

To get to Han Soon Dong Cave, I first flew to the bustling frenetic city of Hanoi, in northern Vietnam, spent a night there exploring the streets, eating in the streetside restaurants on tiny kindergarten sized plastic chairs alongside locals while soaking in the blissful chaos of Hanoi with its choking humidity and mixed architecture of old French and brutalist Communism.  

Amazing streeside eatern in hanoi where fresh foods are cooked in front f you and eaten in small tables on the sidewalk

Amazing streeside eatern in hanoi where fresh foods are cooked in front f you and eaten in small tables on the sidewalk

View from my hotel balcony of crowded, chaotic, dense Hanoi streets 

I then flew to Dong Hoi, located in southern Vietnam just across the old, demilitarized zone that separated the north from south during the war. From Dong Hoi, I traveled north about an hour to a small farming village tucked into the karst mountains near Phong Nha-Ke Bang National Park, which conceals Han Soon Dong cave and dozens of other amazing caves. I stayed in a guesthouse in the village, where I met my guide and prepared for the trekking trip into the cave.

Friendly Vietnamese farmer in traditional hat I met in a farmers market near Phong Nha-Ke Bang National Park

The Jungle Hike

Day 1 we took a bus a few hours through the rolling mountains to the trail head of Phong Nha-Ke Bang National Park, where we began trekking. The initial part of the trek was straight down a steep hill, which reluctantly we knew we would eventually have to climb back up. The trek was though slippery, mud, 100-degree humid tropical heat sometimes in direct sunlight. I couldn’t help but to think of the conditions that American soldiers including my uncle fought in during the Vietnam war and how un-fathomable in the unbearable heat and humidity it must have been especially against an enemy that was at home in such conditions.

We hiked through jungles and meadows in the sun. The forest provided much needed shelter from the sun, but it usually meant more bugs. We crossed fast moving streams that threatened to knock you into the water with their fast currents. Our teams consisted of a group of 20-30 porters, cooks, guides and approx. 6 other foreign tourist cavers-2 that I discovered were also from San Diego. Vietnam regulations capped the number of foreigners that can enter the cave during the course of a week to approx. 6 people. The porters and cooks raced to each campsite and were there usually hours before we arrived. We hiked 35 km each way to Soon Dong cave through wild jungles in pristine condition with jagged limestone mountains containing more caves, some possibly unexplored, all around us. We were hiking through trails that once were part of the Hoh Chi Mon Trail network that the Vietcong and North Vietnamese Army once used to smuggle weapons and supplies to troops in the south to fight the Americans and Vietnamese soldiers would seek shelter in some caves during American bombing raids.

Hiking into the jungle

Crossing rivers

After about 5 hours of hiking, we arrived at an isolate indigenous tribal village of thatched houses with no electricity. Vietnam has many indigenous people comparable to Native Americans in the USA who are indigenous to the region, speak their own language and live off of the land. The tribes that live in the park are allowed to stay as long as they only hunt and farm for subsistence purposes, which is very low impact on the park.

We visited this tribal village and had tea and lunch with them. I took photos with my polaroid camera and gave the children a copy of their photos.

Tribal Village

Chief of the tribal village who invited us in to his house and made us tea. 

Young girl of the tribal village

Many bomb fragments or unexploded ordinances still exist and are washed up by the river every year. Kids will play with them, or villagers will try and recycle the metal. This sometimes causes the bombs to detonate and in this area in the previous year I heard that a few village kids trying to disassemble a bomb to sell the metal to recycling companies blew themselves up and died.

Me next to a bomb fragment from the Vietnam War

Hang En Cave

Before reaching Soon Dong Cave, we arrived at Hang En Cave, which is also massive and wild. To get to Soon Dong Cave, the easiest path was through Hang En cave. The cave was spectacular and at first, I thought it was Soon Dong cave. We clambered down rocks to get to the bottom of the cave where our porters had already set up our tents next to a small clear green lake in the cave. The cave was full of swallows that lived high up in the ceiling. The nests of the swallows are highly prized in Asia as a delicacy and are extremely valuable. As a result, villagers are allowed to climb up via a series of makeshift death-defying vine/rope like ladders to collect a certain number of nests for sale every year.

Me overlooking our campoing area in Hang En Cave

Me overlooking our campoing area in Hang En Cave

We stayed 2 nights in hang En Cave. One-night enroute to Soon Dong Cave and one night on the way out. This was fine with us because swimming in the cool clear lake fed by fresh rivers coming from the interior of the cave felt like heaven after a long day in the humid jungle.  We spent hours just sitting in the lake cooling off while admiring the view of the huge, massive cave chamber. My only grudge with the lake was the annoying minnow sized fish with a foot fetich that would keep nipping on your feet if you remained still too long.

Camping area next to the lake

Camping area

photo I took from the lake

Hiking through Hang En cave

Enormous Exit of Hang En cave-the tiny dots on the cave fllor are the porters in my party carrying food and camping gear to provide scale of how huge the cave is 

The cave swallows live in nests on the side and top of the cave and are not equipped to land on the ground because if they do, they cannot accelerate to take flight again. They are only designed to take flight by jumping from high terrain. We found some on the ground helpless and just waiting for a snake or insect to devour them. So, we tried to help them take flight by climbing to the top of a rock and throwing them up in the air. Sometimes this was successful and sometimes it wasn’t.

Cave Swallow

Soon Dong Cave

From Hang En, we had to hike a few hours through more jungle, rivers and uphill through karst rocky before reaching the entrance of the Soon Dong. The entrance was not impressive and mostly concealed by jungle and it was easy to understand why the cave went undiscovered for so long.  To enter the cave, we didn’t have to abseil by rope into a deep hole. Instead, we had to climb down steep 300-foot series of ledges and to prevent any accidents we did have to tie into rope. Once at the bottom of the slope we were in a small dark section of the cave, but it wasn’t until we started hiking for an hour through a few bat infested pitch-black narrow corridors and crossed a few strong cave rivers when we entered the huge chamber-big enough to fly a 747 through- that the cave is known for. The main chamber was so huge that I could barely see the ceiling of the cave at times and since we were walking along limestone formations that were hundreds of feet above the river that carved the cave, there was still so much more to the cave below us that I also could not see. There were no artificial paths, ropes, lights in the cave. Everything was wild and it was our responsibility to ensure that we didn’t take a wrong step into a crevice in between the rocks. A wrong step into one of these could send you spiraling hundreds of feet into darkness never to be found again.

The conditions of the cave are very tough on cameras and my camera stopped working after a few days in the cave. Luckily a few of the other travelers in the cave allowed me to borrow their cameras so that I could also take photos using my memory card in their cameras.


Hand of Dog Formation in Main chamber of the Soon Dong cave-the light in the middle of the photo is the headlamp of on our my guides that hiked ahead to climb up the giant stalagmite. The clouds are the mist in the cave. The cave is so big it makes its own weather.

Another photo of a cave guide that climbed a massive stalagmite

General conditions of climbing in cave

Scale of immensity in cavern

Million year old fosils engraved in rocks at the bottom of the cave. This part of the cave is under hundreds of feet of water every rainy season when the cave floods. 

me looking at small stalagmites building up at the bottom of the huge cave chamber

Camping in the Cave

We camped 3 nights in Soon Dong cave and 2 nights in hang En cave. We never camped in the darkness since a doline, or hole in the ceiling of the cave which allowed sunlight in was always nearby. Camping in the cave was amazing. Of course, there were challenges such as heat, humidity, general feeling of being filthy and of course bugs and the occasional mysterious creepy crawler on your body at night, but the large crew of cooks and porters ensured that the experience was as luxurious as a camping trip could be. We had incredible Vietnamese food, tables and chairs that were carried into the cave for us. Note: all materials that are not naturally found in the cave are brought in by porters and brought out as well including human waste, which is carried out of the cave.

A typical night in the cave consisted of storytelling around the campfire, drinking rice wine or whisky and watching the porters get insanely drunk and act crazy. It was alright, they worked hard and deserved to unwind. It was surreal to be in Vietnam with our porters and guides drinking rice wine with them while they sang revolutionary hymns celebrating the reunification of the South and North on July 2-Reunification Day, which was only possible after the US military pulled out of Vietnam effectively handing over the South to the North.


My tent with the light coming from a hole in the cave ceiling in the distance

Our cook preparing a meal

Dolines or Ceiling Collapses in the Cave

Sonn Dong cave has two dolines, that break up the darkness of the cave by allowing sunlight to enter in through the ceiling. High walls on both sides of each doline and thick vast jungles prevent access to the cave from them without a lot of work and rock-climbing rope.  Both dolines are incredible but the first one is merely out of this world and looks prehistoric and you wouldn’t be surprised if you saw a dinosaur living inside of it.  The second doline is not as impressive visually, but it is unique in that it has a rainforest inside of it that you need to hike through to get to the other section of the cave.

My group climbing to the doline headlanters lighting their path

One of the dolines with Jurassic park looking cave structures draped in idd an lichen. The otherside of the doline is a 1000′ tall entrance into the cave

Photo taken by a member of my cave party showing one of our guides standing on a stalagmite in a doline with sunlight beaming down on them

Photo taken by a member of my cave party showing one of our guides standing on a stalagmite in a doline with sunlight beaming down on them

Our cave party  standing on a stalagmite in a doline with sunlight beaming down on them

Massive ceiligs that look like alien space ships 

Me sitting in the in the distance admiring one of the dolines with my co-explorers off to the side of the cave

Me sitting in the in the distance admiring one of the dolines

World’s Largest Jungle in the World’s Largest Cave

The 2nd doline, called the Garden of Edam, is the largest jungle inside of a cave in the world. The jungle has 200′ tall rainforest trees and creatures and animals found nowhere else in the world. There are some monkeys, flying fox bats and hornbills that visit the jungle, and it has leeches, which I discovered on my leg afterwards. 

Hiking to jungle doline

Jungle doline

Jungle doline

Campsite near Jungle doline with all gear carried in and out by porters including table

Enormous Stalagmites, Pigmentless Spiders and Huge Mud Pits

We camped the last two nights in the beginning of the cave’s last tunnel just outside of the jungle doline-Garden of Edam. This allowed us to wake up early in the morning and explore the jungle and watch the incredible colors of the early morning sun light and listen to the exotic animal and bird calls.

To get to the end of the cave or the Great Wall of Vietnam as it’s called, the hike from the campsite is approx. 3 hours and the tunnel gets smaller and muddier. Right before the muddy sections of the cave, we passed stalagmites that are larger than anything I have ever seen before, and it would be impossible to believe if I didn’t have photos of me next to them to show their enormous scale. Eventually, huge, towering walls of mud surround us right before you reach the dead end of the cave. Giant white spiders and crickets with no pigment crawled alongside the mud walls as we passed. The guides figured the spiders were venemous but nobody knew for sure since the spiders had never been studied before.

At the end of the hike, we came to a 20-foot-deep mud pit with gradual slopes leading into the pit that formed a kind of natural slide. We all took turns sliding into the pit and rolling around in the mud having the time of our lives before returning on the long hike back to your campsite.

Hiking to the Great Wall of Vietnam

Me near on a giant stalagmite

Me in the foreground

Me at the bottom near the largest stalagmite I have ever seen

After visiting the Great Wall of Vietnam or the wall where the end of Soon Dong cave is located, we camped one more night in Soon Dong cave, hiked to Hang En Cave and camped there one night before hiking out to the road and returning to the village where our hotel is located. We spent one night have a huge incredible meal celebrating our successful cave expedition together with drinks and I continued on with my journey to Hanoi via an overnight sleeper train in a cabin that I shared with other Vietnamese and a crying baby. After Hanoi and traveled onward to Cambodia to visit the wilderness of the wild Cardamon Mountains.

3 + 3 =

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