A team from National Geographic Magazine began their journey to record 360-degree images of Son Doong Cave at Ho Khanh’s Homestay as part of its Son Doong 360 project one day in January.

>> An audio version of the story is available here

Ho Khanh is the name of a local carpenter who found the entrance of the world’s largest cave, Son Doong, in UNESCO-recognized Phong Nha-Ke Bang National Park in the central province of Quang Binh.

Now, Ho Khanh’s Homestay is where most explorers from around the world arrive at before entering Son Doong.

They come not only to stay for a time but also to be told stories about the ‘work of nature’.

The Son Doong 360 project is expected to show exclusive 360-degree images of Son Doong on the online edition of NatGeo.

Son Doong 360 was initiated by Swedish journalist Martin Edström, 27, who graduated from Stockholm Unviersity in 2010 and is now working as a photographer for UNDP and the Kontinent Agency of Sweden.

The cave – formed two to five million years ago by river water erosion of the limestone underneath – was discovered in 1990 but only announced publicly in 2009 thanks to the assistance of British explorer Howard Limbert.

Limbert and his wife Deb have been ‘close friends’ of locals in Quang Binh ever since.

Companions

With an increasing amount of equipment, the Son Doong 360 team finally needed the help of up to 30 porters for a five-day trek across a total of 50km through forests and streams.

After their luggage was loaded on a truck, porters got on a bus while the NatGeo staff and Tuoi Tre (Youth) newspaper journalists boarded a 16-seat minibus.

The team skirted around the woods in Phong Nha-Ke Bang, designated as a UNESCO World Heritage Site in 2003, decorated with the sheer cliffs of limestone mountains.

The team paused at the foot of a mountain which is inaccessible to cars and then had to walk along a path covered by wild flower blossoms.

They then stopped at two large rocks midway down the path to record the singing of wild birds before reaching the mouth of the cave.

The team was welcomed with the first challenge – crossing a stream near the mountain’s foot. It is also the first image of the Son Doong 360 project. Half an hour after crossing the stream, the team set foot in Doong Village with a dozen simple houses under the wild forest.

In the wet season, the village is totally isolated from the outside world. Floodwater bars villagers from leaving it and visitors from entering.

In 2010, Doong villagers had to climb up tall trees to survive floodwaters.

From Doong Village, the team went straight forward to En (Swallow) Cave – the first venue of the journey. Though the path to En Cave was simple, the explorers had to cross 20 sections of streams with water reaching their knees.

That is why the trip was called ‘the journey of wet feet’.

Explorers cross a brook on the way to Son Doong Cave. Photo: Tuoi Tre

Images of the streams are included in the Son Doong 360 project. It took a lot of time to record these pictures and the singing of birds.

The upper mouth of En Cave appeared halfway up the side of a limestone mountain. However, the explorers decided to enter the lower mouth, which is not high but wide. At the center of the cave’s mouth is a rock pillar.

Looking out from inside, the mouth is like two huge windows to receive sunlight. The shadows of people standing at the mouth of the cave are as small as ants crawling along a river.

The cameramen asked other team members to stand still for around ten minutes to take images of the ‘windows’.

One can hear clearly the brook murmuring down and the singing and flapping of wings of swallows from the other side of the cave.

Going deep into the cave, the team crossed a brook to reach a bank of rocks and a small hill. They chose a flat area to camp on the other side of the hill inside the cave.

The rocky bank is actually a bank of sand poured into the cave by a river flowing under a 100m-high arch inside the cave.

Crossing the rocky bank, the team took images of a bank of 'sandy mushrooms'.

The ‘mushrooms’ were formed by gravel and grains of sand over millions of years.

Although the temperature in the central region is hot and muggy, the water in the lakes inside the cave is always around 19 degrees Celsius, British explorer Limbert said.

A bank of 'sandy mushrooms' that was formed hundreds of thousands of years ago. Photo: Tuoi Tre

First achievement

At 7:00 pm, after dinner, no more sunlight was visible at the cave mouth, and the generators began working.

The explorers began assembling images they took throughout the day to create 360-degree images of Son Doong.

The difficulty of taking 360-degree images is that they require similarity of light while taking different images before assembling them. A small change in light will spoil the work of an entire day.

The first 360-degree image was set up, and it was perfect. The team cheered one another.

Looking at the image, one can see brook water flowing, weeds, dry leaves, gravel under water and so many other animated details.

At 11:00 pm, the last job of the day was to prepare equipment for the following working day.

The Tuoi Tre journalists learned “God Morgon!” in Swedish (meaning “Good Morning” in English) to prepare to greet each other the next day.

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