At the beginning of 2015 we were lucky enough to take part in a 5-day expedition to Hang Son Doong, the world’s largest cave. Run exclusively by the adventure tour company Oxalis, we had been spending a few months in the town of Phong Nha, close to where the cave is located. Through a number of cancellations and an opportunity to do some work with Oxalis, we had been given the opportunity to visit this true wonder of the world.

Hang Son Doong was discovered in 1990 by Ho Khanh, a local man who was out hunting in the Phong Nha-Ke Bang National Park. While seeking refuge from an approaching storm he found a large opening in the side of a cliff, with clouds billowing out. He neared the entrance and could hear a river deep inside. The steep and dangerous rocks meant that Ho Khanh was unable to explore further, and he left once the storm passed.

Around the same time Howard and Deb Limbert, two caving experts with the British Cave Research Association, were living in Phong Nha spelunking in the area. Over dinner one night Ho Khanh mentioned his find to Howard and Deb, but admitted that he had now forgotten where it was. Knowing that the presence of clouds and an underground river meant something substantial was there, Howard and Deb urged Ho Khanh to try and find it again. For the next two decades their search turned up nothing.

Ho Khanh Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

Ho Khanh, the local man who discovered Hang Son Doong. We were lucky enough to have him join us on our expedition.

However things were to suddenly change, and in 2008 while on another hunting mission Ho Khanh found himself in a section of the jungle he recalled to be near the entrance he found all those years ago. He managed to find it, and carefully retraced his steps back to Phong Nha village to report his discovery to Howard and Deb. The monsoon season soon kicked in, and the exploration would have to wait until the following year.

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In 2009 Ho Khanh returned, this time with the aid of the BCRA. They began their exploration of the cave, which led them to a giant wall that hindered any further progress. In 2010 they managed to scale the wall, which they called the “Great Wall Of Vietnam”, and find the other exit to the cave. At this point they realised that the cave was the biggest ever discovered. Named Hang Son Doong, meaning “Mountain River Cave” in Vietnamese, it is now open to small expedition groups.

The discovery of the world’s largest cave in one of the poorest provinces in Vietnam has brought about an incredible surge in community-based tourism, which is positively affecting the lives of many locals. Besides the ecological marvels of what lies beneath the jungle, the way people are able to benefit their lives from its existence is one of the real wonders of Hang Son Doong.

More people have stood on the summit of Everest than have stood inside Hang Son Doong, and we were one of the lucky few to get to experience this impeccable adventure. This is our photo journey to the heart of Hang Son Doong.

Sunbeam Doline 1 Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

With the colossal size of the caves in the Phong Nha-Ke Bang National Park and the high levels of rainfall the region receives, erosion happens at an accelerated rate. Occasionally the weight of the limestone gives way and collapses, creating what is known as a ‘doline’. Derived from the Slovenian word ‘dolina’, meaning ‘valley’, these sinkholes create huge gateways to the outside world. At certain times of the year when the conditions are right, incredible sunbeams penetrate through these exposed sections and into Hang Son Doong, creating mesmerising light shows.

Hang En Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

On the first day of the 5-day expedition you reach Hang En, the third largest cave in the world. Meaning “Swift Cave”, Hang En has been used by local tribesman for time unknown. They have been discovered free climbing the dangerous cliffs in search for the swallows that live in the cracks – considered a local delicacy. The minority groups are never seen during the tourist season though, and the inside of Hang En serves as a base on the first and last nights. This campsite is perhaps one of the most spectacular in all of Asia.

Chamber Of Light Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

The cave systems of Phong Nha are immense, and the national park contains the current title holder for the largest ever discovered, Hang Son Doong. Interpreted as ‘Mountain River Cave’, the largest chamber measures 5km long, and peaks out at 200m high and 150m wide. The only way to get a true sense of perspective on the sheer size of Son Doong is to have fellow trekkers scatter throughout the limestone galleries. Even then it is hard to properly comprehend the enormity of a place that could house an entire New York City block, all underground.

Porters Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

In the same way the Sherpas of Nepal are instrumental to a climber’s success in summiting Mount Everest, the local porter’s of Son Doong are the true heroes of this multi-day caving expedition. These men all hail from Quang Binh, one of the poorest provinces in Vietnam, and come from a variety of working backgrounds such as farming, hunting and logging. One thing they all have in common is their astounding ability to survive and thrive in the jungles of Phong Nha. Twenty porters, two chefs, two national park rangers, two assistant guides, one lead guide and two British caving experts make up the team that take a group of ten customers on the 5 day, 4 night journey inside the world’s biggest cave.

Hang En Exit Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

This exit of Hang En is one of the largest ever discovered. From the sand to the ceiling is over 120m tall, and the width is over 140m. Caving experts believe this to be close to the maximum size possible, as the weight of the limestone above could force a collapse at any time. To get a true scale of the immensity of this exit, study the size of the people standing in the centre of the opening.

Porter Sandals Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

Many people who undertake serious outdoor expeditions spend hundreds of dollars on specialty shoes armed with the latest in adventure footwear technology. The jungle men of Phong Nha wear plastic sandals purchased from the local market at the cost of 20’000 Vietnamese Dong – the equivalent of about US$1. They nimbly skip from boulder to boulder, ford fast-flowing rivers and trek for weeks on end through dense forest wearing these basic shoes. Observing foreign tourists struggling to negotiate the difficult terrain in sometimes thousands of dollars worth of gear is fascinating to the porters, who are quite content with their chosen footwear.

Descending Into The Darkness Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

Some sections inside Hang Son Doong require specialist equipment, such as a harness, belay devices and safety lines, in order to safely manoeuvre over cliffs and boulders. Under the supervision of experienced guides we scramble amongst tumbled limestone, sometimes with sheer drops either side of us. While the climbing required is far from being technical, an adequate level of fitness and ability is needed to pass through the majority of the cave. Within minutes we can escape from the outside world and descend into total darkness.

Limestone Formation Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

Limestone formations such as stalagmites and stalactites are formed when water containing dissolved calcium carbonate drips through the cave’s ceiling and creates minuscule rings. Over millions of years these tiny minerals grow in a collection of striking and often beautiful shapes. The development is very slow, varying between 0.007mm and 1mm annually. Research in Vietnam has never been specifically undertaken to see exactly what the localised rate of growth is. The general consensus is that it is much higher than average, due to the average 2500mm of rainfall received every year and the high levels of condensation that build up inside the caves. As a result the formations in Phong Nha are amongst the biggest found anywhere in the world, such as one 80m high stalagmite in Hang Son Doong – the tallest ever discovered.

Cave Pearls Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

It’s not just the enormous formations which are incredible inside Hang Son Doong. Also discovered are rare, spherical limestone pieces known as “cave pearls”. These are formed from a tiny nucleus spinning over thousands of years, collecting calcium salts as layers.

Porters Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

Entertainment comes in many forms when you spend days on end inside a cave. Card games are popular, as is singing songs and drinking potent, locally brewed rice wine. The Vietnamese porters take pride in their strength and agility and are constantly challenging each other to show off their skills. Arm wrestling is one such activity and the men enthusiastically try to get everyone involved. Despite their small stature, their levels of energy and strength are impressive and they constantly out-perform professional athletes who come to explore the caves.

Campsite Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

Camping inside Hang Son Doong is quite possibly the most unique and incredible experience you can have anywhere in the world. Every season the porters carry in enough equipment to create the site, including tables, chairs and even toilet facilities. At the end of the season everything is carried out, including the waste.

Jungle Clouds Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

Hang Son Doong is so massive that it contains its own jungle, underground river and localised weather system. Clouds form inside the cave and spew out from the exits and dolines, which gave the first explorers a clue as to how large Hang Son Doong really is. As you trek through this section of the cave, known as the ‘Garden of Edam’, clouds filter through the trees creating a prehistoric atmosphere. Completely engulfed by karst cliffs and towering foliage, with a vast exposed ceiling above you, it is easy to forget that you are actually deep inside an underground cavern.

Underground River Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

The Rao Thuong River flows fast through the Son Doong cave system, continuously carving new chambers and passages. During the wet season the river floods to dizzying levels, halting any chance of exploration through the caves or jungle. The water shines in bright hues of blue and green as a result of most of the sediment being filtered out by the limestone. Rao Thuong River must be crossed numerous times in order to reach the giant cave system. Once inside, a guide rope is used to assist in fording sections of the river safely.

Watch Out For Dinosaurs Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

The viewpoint looking back at “Watch Out For Dinosaurs” offers a truly magnificent sight. Clouds roll in from the jungle outside, and with the right conditions small waterfalls tumble down, creating a visual experience like no other.

Campfire Cooking Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

When the porters and caving experts are on their exploratory missions in the national park, they live on a staple diet of rice and whatever they can harvest from the jungle. In stark contrast, the official tours to Hang Son Doong have two qualified chefs as part of the experienced team. The communal dinners sitting in the shadows of the world’s biggest cave are all the more impressive when you are eating barbecued pork ribs, fried chicken, sautéed vegetables and seasoned tofu. High energy tours require high energy foods, and there is no shortage in the 45kg packs the porters bring with them.

Stars Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

The location of the second camp inside Hang Son Doong lies at the bottom of a steep rockfall coated in moss and shrubs. From your tent you can stargaze up through Doline 2, while the dark abyss of the rest of the cave menaces directly behind you. The local porters all favour this particular campsite over the others. Most of the local men are very superstitious and maintain a deep fear of caves. They take comfort in being able to stare up at the jungle and open sky. To them, the jungle is home and always will be.

Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

In this shot Lesh stands behind the campsite in Hang En, where a narrow slit allows passage between both exits.

Proposal Engagement Hang Son Doong Photography Tour World's Biggest Cave Vietnam Phong Nha

At the base of Doline 1, having just moved through Watch Out For Dinosaurs, I asked Alesha to step up onto a limestone formation for a photo. With the rare sunbeam glowing brightly behind us, we looked into each other’s eyes. She asked me how we should stand for the photo, and I said that I had an idea. At this moment I dropped to one knee and told her that my love for her was larger than anything in this world, the cave included. With a tear welling up in my eye I asked the girl of my dreams to marry me. She closed her eyes, started crying and said “yes”.


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Hang Son Doong, Phong Nha National Park, Vietnam

Alesha And Jarryd

Hey! We are Alesha and Jarryd, the award winning writers and photographers behind this blog, and we have been travelling the world together since 2008. Adventure travel is our passion, and through our stories and images we promote exciting off-the-beaten-path destinations and fascinating cultures as we go. Follow our journey in real time on Facebook, YouTube and Instagram.

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