A Week of Adventure in the World’s Largest Cave-Hang Son Doong

July 2014: I first learned about the great cave when I flipped open a National Geographic magazine and saw photos of a place so vast and otherworldly that it seemed almost impossible to reach. It looked like something out of a dream—a hidden world so massive and untouched that I assumed only elite scientists with special government permits could ever set foot inside.

But the more I researched, the more determined I became to find a way in. If I had to, I was prepared to sneak in with the help of local indigenous tribes. However, in the end, I managed to gain access legally—by joining a weeklong paid expedition.

The cave was heavily protected by the Vietnamese government, with only one company authorized to operate tours. This local Vietnamese company was managed by a British caver who had been part of the first exploratory expedition into the cave in 2009. Before that, the cave, hidden deep within a wild, mist-shrouded stretch of mountainous jungle, had remained completely unknown—no documented human had ever set foot inside.

Since no other tour operators were allowed access, my group of just five to seven tourists, accompanied by a team of 20 to 30 porters and guides, would have the entire cave complex to ourselves for the week. I had been fortunate enough to sign up for one of the first-ever tourist expeditions into this mysterious underground world.

This was the cave of my dreams—the kind of place I had been searching for my entire life. And this is the story of my adventure.

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

Hang Son Doong is located near what was once the demilitarized zone that divided North and South Vietnam during the war. The surrounding jungle-clad mountains remain wild, home to a network of other caves that once served as sanctuaries for the Viet Cong, where they hid from relentless American aerial assaults. Even today, the jungles are home to wildlife such as gibbons, and though rare, some elephants and tigers still roam the region. One of our guides mentioned that he had seen a tiger a few years ago, though I wasn’t fortunate enough to spot one myself.

Hang Son Doong holds the title of the largest cave chamber in the world—so massive that a Boeing 747 could fly through it with plenty of room to spare. A river winds through the cavern, and access is strictly seasonal. During the rainy months, the cave floods, making it impossible to enter, so expeditions are only possible in the dry season.

Entering Hang Son Doong requires a special permit from the Vietnamese government, and only one authorized operator is allowed to bring tourists inside. Strict visitor limits and conservation rules are in place to protect the cave, ensuring that this underground wonder remains as pristine as the day it was first explored.

To reach Hang Son Doong Cave, I first flew into the frenetic, bustling city of Hanoi in northern Vietnam. I spent a night exploring its lively streets, dining at streetside restaurants on tiny, kindergarten-sized plastic chairs alongside locals. The air was thick with humidity, the scent of sizzling food, and the constant hum of motorbikes weaving through the chaos. As I wandered, I soaked in the city’s striking contrast of old French colonial architecture and stark, brutalist Communist-era buildings—a fusion of history and modern energy that made Hanoi feel both overwhelming and exhilarating.

Amazing streetside eatery in Hanoi where fresh foods are cooked in front of you and enjoyed at small tables on the sidewalk

Amazing streetside eatery in Hanoi where fresh foods are cooked in front of you and enjoyed at small tables on the sidewalk.

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

From Hanoi, I flew to Dong Hoi, a city in southern Vietnam just beyond the old demilitarized zone that once divided North and South during the war. From there, I traveled about an hour north to a small farming village nestled in the dramatic karst mountains near Phong Nha-Ke Bang National Park—a region that conceals Hang Son Doong along with dozens of other extraordinary caves. I stayed in a guesthouse in the village, where I met my guide and made final preparations for the trekking expedition into the cave.

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

We set off by bus, winding through rolling mountains for a few hours before reaching the trailhead of Phong Nha-Ke Bang National Park, where our trek began. The initial descent was straight down a steep hill—a fact we reluctantly acknowledged, knowing we would eventually have to climb back up on our return.

The trek was grueling—thick, slippery mud, 100-degree tropical heat, and oppressive humidity. At times, we hiked in direct sunlight, sweat pouring down as we trudged through the relentless terrain. I couldn’t help but think of the brutal conditions American soldiers, including my uncle, had faced during the Vietnam War. It was unimaginable—fighting in this unbearable heat and humidity against an enemy who thrived in it.

We passed through dense jungles and open meadows, the forest canopy offering some relief from the sun but introducing an entirely different challenge—swarms of bugs. Fast-moving streams crossed our path, their currents strong enough to knock us off our feet if we weren’t careful.

Our team consisted of around 20 to 30 porters, cooks, and guides, along with approximately six other foreign tourists—two of whom I discovered were also from San Diego. Vietnamese regulations capped the number of foreigners allowed to enter the cave each week to just six people, ensuring minimal impact on the pristine environment.

The porters and cooks were a force of nature. They raced ahead of us, reaching each campsite hours before we arrived, setting up everything in advance. We trekked 35 kilometers each way to Hang Son Doong through untouched jungle, surrounded by jagged limestone mountains concealing countless caves—some of which had never been explored.

We were walking through history, following trails that were once part of the Ho Chi Minh Trail network. During the war, the Viet Cong and North Vietnamese Army used these very paths to smuggle weapons and supplies to the south. Many of the caves in this region had served as shelters for soldiers during relentless American bombing raids. As I hiked, I couldn’t shake the weight of the history beneath my feet.

Hiking into the jungle

Crossing rivers

After about five hours of hiking, we arrived at a remote indigenous tribal village, a collection of thatched houses with no electricity. Vietnam is home to many indigenous groups, comparable to Native Americans in the U.S., who have lived in the region for centuries, speaking their own languages and relying on the land for survival. The tribes within Phong Nha-Ke Bang National Park are allowed to remain as long as they only hunt and farm for subsistence, ensuring a minimal impact on the environment.

We spent time in the village, sharing tea and lunch with the locals. As we sat together, I took photos with my Polaroid camera, capturing moments of their daily life. I handed copies of the photos to the children, who marveled at seeing their own faces appear instantly on the prints. Their excitement and curiosity made for a memorable and heartwarming experience.

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 and unexploded ordnance still litter the landscape, with some washing up along the river each year. Children sometimes play with them, unaware of the danger, while villagers attempt to salvage the metal for recycling. Tragically, this can lead to deadly accidents. The previous year, I heard about a group of village children who tried to disassemble a bomb to sell the metal—only for it to detonate, killing them instantly.

Me next to a bomb fragment from the Vietnam War

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

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

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

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

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

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.