Journey Through the Largest Cave in the World

Son Doong Cave—the largest in the world—wasn't discovered until 2009. Now, National Geographic grantee and photojournalist Martin Edström, takes us deep inside Son Doong as he tries to capture its overwhelming size and beauty in 360 degrees.

The effort to share Son Doong (also known as Hang Son Doong) with the world has been decades in the making. "There was a local farmer who found what he thought was an entrance to a cave in the ‘90s, but it was this big, black hole in the ground where no one dared to go," Edström says of the cave, which is obscured by a dense Vietnamese jungle. "The farmer alerted some local experts and they tried to go there again, but he couldn't find his way back. Then in the early 2000s, he finally managed to find it again with a team of scientists, and they were able to go down into the cave and that's when they realized this was something huge."

The farmer, Hồ Khanh, is actually part of a 40-person team helping Edström complete the elaborate task of documenting the exquisite cave. To stitch together just one 360-degree image can require up to 400 photos, and it often takes a couple hours to light a scene before Edström can even begin taking photos. "We have 16 cameras of different kinds, we have 20 kilograms [45 pounds] of batteries just for the big lamps that we are going to use to light up the cave. We have ropes, we have harnesses, everything you need to go through the jungle, down into a cave and do a big technical camera project like this," says Edström.

The more challenging—and stunning—images are the result of what is perhaps Son Doong's most surprising feature. "We have rappelled down into the darkness, we can see nothing but our headlights and then really, really far—kilometers away up ahead—inside the cave, we see the first glimpse of daylight,” Edström recalls. “It’s a really insane moments when you realize you’re are walking through a big, dark cave and you're going towards daylight that's actually inside the cave."

The daylight streams in through Son Doong's two giant dolines—or sinkholes—in its ceiling. "Scientists estimate that these sink holes were formed hundreds of thousands of years ago as the roof collapsed. These caves are formed by rivers slowly running through and at one point in history the cave ceiling was way too weak and it collapsed, creating these holes and letting daylight in. From that moment, life could begin to form. That's why we have these fantastic forests and alien landscapes that are a veritable jungle inside the cave," explains Edström.

The juxtaposition between the cave’s darkness and the daylight falling in from above proved difficult to capture in photographs, says Edström. "We had to counter the sunlight with our own LED lights inside the cave and make sure that we've got enough good exposures on both sides. This was really, really hard and we had to work for hours to get the lights in the correct positions and make sure that once we sit down and render these images, we have enough data or enough exposure to show off both the fantastic greenery that's in the daylight, but also the other side; the darkness, the more dead part of the cave, but that's just as beautiful."

For Edström, documenting this natural marvel is about way more than pretty pictures. "We have to preserve Son Doong. We want people to be able to enjoy it, of course, but it has to be some kind of middle ground. When we heard the news that they wanted to build a cable car system through this cave—that would be an absolute offense to the pristine conditions that we found it in just a few years back."

Edström hopes his images will convince others to feel the same sense of gravity toward protecting Son Doong. "I hope that the audience can really feel that they've somehow been there, even if it's a virtual digital journey, because what I want to convey is the feeling of being there, about walking through this pristine beautiful place, this cave in Vietnam and making people realize that places like these are part of our heritage that need to be preserved."

Dive into Edström's images to take a 360-degree tour of Son Doong Cave.

Watch the entire Expedition Raw series.

SERIES PRODUCERS: Chris Mattle and Jennifer Shoemaker
GRAPHICS: Chris Mattle
FOOTAGE AND IMAGES: Martin Edström, Mats Kahlström, and Erik Hinnerdal