Step underground into the world’s largest cave: Hang Son Doong

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Fitting a whole New York City block and a weather system that creates its own clouds, Hang Son Doong is truly a spectacular underground world.

Hang Son Doong, Vietnam

Quang Binh province in Central Vietnam is home to UNESCO protected Phong Nha-Ke Bang National Park – a vast, mostly untouched land of lush forest, sprawling rivers, and mysterious caves. It is here you will find Hang Son Doong, or Mountain River Cave, a mammoth of a space that stretches for over three miles (five kilometers) and reaches heights of 650 feet (200 meters). 

Formed during the Cambrian-Permian geological era, the karst system found in Phong Nha Ke-Bang National Park is around 400-450 million years old and is the oldest in Asia. However, Son Doong cave, nestled within these peaks, is relatively young, only about three million years old. The cave was also discovered just about 25 years ago in 1990. This means that if you’re one of the lucky few to be able to venture inside, you will enter a world that has been left devoid of humans and virtually unchanged for millions of years. 

A cave so large, it creates its own clouds

The main cavern of Son Doong is so massive that it could fit an entire New York City block inside. Imagine that. Plus, that’s just the main cavern. The whole system is much, much bigger, that it contains its own thriving ecosystem – a jungle home to a variety of wildlife, an underground river, and even a localized weather system that creates its own clouds. Not to mention the large creepy crawlies that are reminiscent of early times.

Hang Son Doong

There are also multiple dolines. These are sections of collapsed limestone ceiling, creating an opening of sorts. Through these dolines, sunbeams creep through dense foliage. You’ll hear the sounds of birds and macaque monkeys echo off the limestone and all this in harmony with the soft gurgle of the river inside. In one chamber, you will also find the largest stalagmite known to man. It hangs at 262 feet tall (80 meters). 

Getting to Phong Nha is very easy

To get to Phong Nha, you can either make your way downward from Hanoi or upward from Ho Chi Minh City. It’s about a 1,250 kilometer (777 mile) journey from HCMC, so it may take you a while by bus, but it’s actually not that bad when you make multiple stops in between. There is also the train, the Reunification Express, that allows you to sleep comfortably, but make sure you book in advance.  

From Hanoi however, the distance is much shorter, 496 kilometers (308 miles), and from here you can take a single-journey sleeper bus. The bus takes about 10 hours and will cost you just about $15 USD. These buses also run at night, so you will wake up fresh and ready for your once-in-a-lifetime adventure. 

To cut down on time, you can book flights from both Hanoi and Ho Chi Minh City to Dong Hoi, and from there you can take a bus to Phong Nha. You also have the option to take a bus from Ninh Binh, one of the more common routes to take.

Vietnam Airlines is the only airline that offers these routes, and there aren’t many options within a day. Taking a flight may save time, but it is not flexible, nor is it fun. You may miss out on a lot of interesting sights on the way. Vietnam really truly is so unique in every aspect, that we recommend you stick to ground transportation.

A thrilling journey through dense forest, crossing rivers, and sleeping under the stars…

Luckily, anyone is able to experience the mysteries of Hang Son Doong. However, getting to the cave itself is not easy. The experience begins with a six-kilometer hike through the rainforest and past the only village located inside Phong Nha Ke-Bang, Ban Doong. This village is home to around 40 of the Bru-Van-Kieu ethnic minority.

The Quang Binh province has long been one of the poorest regions in the country, heavily bombed during the Vietnam War, and never quite recovered. The discovery of the cave turned this around, especially for the villagers of Ban Doong. They embraced this new opportunity and the result has seen the local economy flourish. 

Exploring this village and interacting with the locals is an exciting part of the journey. The two elders of the village happily welcome trekkers and share with them a part of their lives. It’s a wonderful glimpse into a way of life that still retains centuries-old traditions while embracing some of the new.

The journey to Ban Doong is the easiest part of the tour. From there is a two-day intense trek through the jungle, crossing various rivers, and camping under the stars. All this just to reach the entrance. Once inside the cave, the adventure steps up a level. You will have to abseil, climb, crawl, and swim through underground rivers to complete your journey. Nights are spent camping by the dolines, under starry night skies undisturbed by light pollution. 

A $3,000 USD price tag for a once-in-a-lifetime experience

Because of how valuable the cave is to the world and especially to the scientific community, there is only one company that has acquired a legal permit to run expeditions into the cave: Oxalis Adventure Tours. By limiting the tour to only one operator, the cave and the surrounding is protected from mass development. 

Hang Son Doong Cave

This four-day expedition costs just a mere $3,000 USD. If you are able to afford this, then great. But there are other requirements. Not only do you have to be extremely fit to partake in the expedition, but also extremely patient, as there is a waiting list of about two years. The government only releases around 300–500 permits yearly. 

The hefty price tag comes with many benefits. You will not be going on this expedition by yourself. There will be a maximum of 10 travelers sharing this remarkable experience, and in addition, your group will include two caving experts, three local guides, two chefs, two park rangers, and 20 porters that will help carry your belongings and other luggage such as tents.

Just like the sherpas of Nepal, it’s the porters of Phong Nha who are the unsung heroes that make the adventure possible. Thanks to them and the rest of the crew, everyone’s safety and happiness is ensured, as is the preservation of the cave. Camping and caving equipment, safety gear, four meals a day, bottled water, and even medical rescue equipment are included in the price.

Inside of Hang Son Doong

The tour runs just once per week between February and August. During the wet season, the Rao Thuong river floods to dizzying levels, halting any chance of exploration through the caves or jungle. 

All thanks to one humble farmer

Son Doong would have remained hidden if it wasn’t for a local farmer by the name of Ho Kanh. One day in 1990, Mr. Kanh was seeking shelter from a passing storm in the jungle and happened upon an opening to the cave. Amazed at the sight of clouds and the sounds he heard from the inside, he wanted to venture further in but was afraid to do so alone knowing how difficult it would be to find him should something happen.

He went home with the intention of coming back, but unfortunately, he was unable to relocate the entrance upon his return. For eighteen years, the location of the cave remained lost. Until Ho Kanh found it again, this time while he was just on his daily grind in search of food and timber. Learning from his mistakes, he marked down clearly where the entrance was and then he subsequently led Howard and Deb Limbert of the British Cave Association to the cave for the first ever expedition. Only in 2013 was this underground world opened to the rest of us. 

Posted December 10, 2020
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Piumi Rajapaksha
Third-culture kid, hailing from Sri Lanka. Currently residing in Ho Chi Minh City, Vietnam and refuses to leave because of the good food. You'll probably find her wandering aimlessly through the city with a coffee in hand looking lost, but she never is.
image of blog writer Piumi