Photographer Jason Speth Takes Us Through Earth’s Largest Cave

What do you wear when exploring the unknown depths of the world’s largest cave? Walter Sky, of course. We had photographer Jason Speth put our complete kit to the test in Vietnam’s Son Doong Cave (where he became the 100th person to have ever set foot), and the outcome? According to Jason, his clothes never smelled—and that’s undoubtedly the best testimonial we could ask for. Read on for more about the photographer’s journey to the globe’s most enigmatic, dangerous cavern.

How did Walter Sky enable you to make the most of your experience in the Son Doong Cave? What pieces did you bring along?
It being my third time through the cave, I had a pretty good idea of what gear worked for me and what didn’t. Clothing is a huge part of comfort and general safety on trips like these. The WS-B02 jogger-style pants I wore while exploring the caves held up and performed unbelievably well. On previous trips, I had worn many different types of lightweight trekking pants. Some were just too hot, others tore or ripped too easily. The pants not only kept my legs cool, but they held up under all the trekking and climbing we had to do. I still wear those exact same pair of pants all the time and they look no worse for wear.

Aside from function, I really do dig the way they look and fit. I love that I can wear the Walter Sky joggers and look professional and stay cool at the same time. Those same pair of pants I wore for a week straight, I also wear to fancy dinners and such. Shirt wise, I brought three total—two WS-T01 tees and one WS-T02. As with the pants and shorts, there's a bit of stretch to the shirts which make things like hiking and climbing and moving around in general much easier and less restrictive.



I also took a couple pairs of merino wool socks which fared very well. Socks and footwear are arguably the most important part of a trip like this. We were trekking and climbing over 20 miles through the cave system and surrounding jungles with our feet constantly getting wet—so if your socks fail, you’re going to be in bad shape. The Walter Sky merino wool socks, like everything else, performed incredibly well.

Oh, and the hat! I can’t forget the hat. In the caves you have to wear a helmet because it has your headlamp attached and it also protects your noggin, but in the jungles I would wear the Walter Sky unstructured hat. I could take it out of my bag pocket without the shape getting all messed up from being crumpled up and throw it on. I’d dunk it in the river and put it on my head to cool off. Overall, it just felt way more breathable than any other hats I've worn.

Tell us more about the Son Doong Cave and why it's special.
Only recently discovered, the Son Doong Cave is the largest known cave by volume in the world. It has caverns where you can fit a 40 story building and passages through which you could fly a 747. Two major roof collapses have allowed for jungles and other life to thrive that are not typically found in caves of this type. Having been undetected for so long, Son Doong is one of the most well preserved and untouched ecosystems on earth. Due to the need for technical climbing equipment to descend into the cave, there has been no evidence suggesting humans have even been inside prior to 2009.

How did you first learn of the opportunity to go there?
Back in 2014, I had seen an article that National Geographic had done on the Son Doong touting it as this new cave that no one had ever really been in. I believe it was Carsten Peter who had these amazing photographs of these huge caverns where the people were just tiny dots, measuring a couple pixels big. There were waterfalls, jungles and rivers, all inside of a cave. I had never seen anything like it.



I learned of a company called Oxalis that had teamed up with the BRCA and began leading expeditions into the cave. So, I contacted them about doing some photography and marketing work and ended up tagging along with one of the expedition groups into Son Doong. That first trip was the longest I’ve done there (about a week inside) and the most physically taxing. It absolutely blew my mind and I instantly fell in love with the place.

Being somewhere where only a very few people had ever been before in the entirety of human history (at that time I was maybe the 100th person to see it), I remember sitting there for a while at a loss for words. I stared at my surroundings for a long period of time before I shot a single photo. That feeling of true exploration and discovery is something that is getting harder and harder to find in this world. This is what I had spent half of my life chasing.

What's the trek like to access the cave?
The trek to the cave starts at a road at the top of a valley, which is actually an extension of the Ho Chi Minh Trail used during the war. It’s mostly steep jungle and river crossings for about a day until you reach a cave called Hang En, which is the third biggest cave in the world. From there you must follow along the Son River for a couple of hours before heading up into the mountains to reach the entrance of Son Doong Cave.



Once inside the entrance, you have to repel down the side of the cliffs that slope down into the cave proper. After that, it’s a series of bouldering, river crossings, jungle sections, rock piles, mud pits, swarms of bugs and steep climbs, all for the most part in complete darkness. It’s really hard to put into words if you’ve never been in an environment like that. That’s why I’m a photographer—I’m much better at conveying the world that way. All I can say is that’s it not easy by any means. The cool things in life rarely are.

How did the Walter Sky pieces endure in the wet conditions that you were in?
The issue with trekking through the Son Doong Cave is that due to the humidity, nothing really dries. If you’ve ever had wet clothes for a couple of days, you know they can get that gross mildewy smell—and that’s the last thing you want to be carrying around with you. The shirts I wore throughout the trip never smelled once. When they got dirty I would also wet them down, wring them out and they wouldn't get wrinkly (which was an added bonus because I looked pretty good even after trekking miles through the rivers and muddy jungles).

Overall, the clothing made such a big difference as opposed to my previous expeditions there. I’m planning on returning next year, and I’ll obviously be wearing all Walter Sky.