Indefinitely Wild

The Best Underwear for the Outdoors? A Speedo.

Probably the most embarrassing article I’ll write this year is also, for your crotch, the most important

My oldest pair still cleans up good enough for a photo. (Wes Siler)
Photo: Wes Siler

When you buy something using the retail links in our stories, we may earn a small commission. Outside does not accept money for editorial gear reviews. Read more about our policy.

Underwear needs to be supportive and comfortable. Outdoors, it needs to breathe well and dry quickly. On longer trips, it needs to maintain its stretch and support, not pick up too much stink, be easy to clean, and strongly resist wear. For years, I've struggled to find an adequate solution. Then I read a news report about the prison in Guantanamo Bay. 

First, some background on my quest. During athletic activity—running, jumping, climbing, crawling, and cycling—you want to have everything down there packed away tightly, where it’s safe from twisting, binding, and yanking. Over long durations of those activities, you need to be able to achieve that control without chafing. Those concerns pretty much eliminate loose boxers or going commando. 

Because of that need for control, I’ve always found the tight, elasticated leg openings on briefs superior to the more fashionable, but looser legs of boxer briefs. So, at home, I wear traditional cotton items. If they get soaked with sweat during a strenuous workout or hike, I’ll simply swap them out for a fresh pair. But that’s not necessarily an option, or a good idea, outside. 

Due to the hollow structure of its fibers, cotton soaks up huge amounts of water—up to 27 times its own weight. Because those fibers naturally carry a negative charge and H2O is positively charged, water molecules chemically bind to cotton, meaning it takes forever to dry out. Get your cotton underwear soaked in sweat, and at best it’s super uncomfortable. At worst, it might contribute to hypothermia. 

So a bunch of companies produce outdoor-specific undies from merino wool. Like all wool, merino is naturally temperature regulating—it’s cool when it’s hot out and warm when it’s cold. Thanks to merino's very fine fibers, it's softer against the skin than other wool varieties. Its fibers are also coated in lanolin, which is naturally anti-bacterial and anti-fungal, meaning wool undies are strongly resistant to developing odor.

But one thing merino can’t do is retain its shape. Even with the help of an elastic thread woven into the merino fiber, every pair of merino wool undies I’ve ever worn has gotten stretched out after only a day’s wear, causing it to lose its ability to provide support and creating uncomfortable bunches when worn under tight clothing or a climbing harness. 

Most synthetic materials that underwear might be made from are very good at wicking moisture, but quickly become breeding grounds for the bacteria in all that sweat. And that makes them smell terrible after even a single day of use. And those thin, made-for-breathability materials that work so well as base layers are again unable to provide the consistent, strong elasticity that underwear needs in order to provide support. Even a pair of $60 Polartec Power Grid boxer briefs stretches out so much during a hike that I’m left with an uncomfortable degree of flop afterwards. That’d be even worse several days into a long-distance backpacking trip. 

I've struggled through all the inadequate solutions described above. If I wanted to be comfortable, I needed to carry a fresh pair of cotton briefs for every day of a long-duration trip. But that added weight and ate up space in my pack. If I wore something else, I risked a very embarrassing injury. Nothing smelled good, nothing really held up, nothing stayed dry, and nothing delivered adequate protection. Then I read that news story about the awful conditions inside Guantanamo and the kind-hearted guards who were risking their own freedom by smuggling in supplies that could enable the prisoners to be a little bit more comfortable.

They were smuggling in Speedos. 

The constantly wet, unsanitary conditions inside the notorious prison reminded me of my own camping trips, and because I grew up swimming competitively, I had a few old Speedos in the back of my closet that could still be coaxed into fitting. The next time I went backpacking, I wore one, didn’t pack anything else, and came home days later with a happy crotch. 

Speedos are made from spandex. As you’re undoubtedly aware, that material is hugely stretchy, very strong, breathes reasonably well, and dries out almost instantaneously. Those merits are what make a Speedo the perfect performance underwear. 

Of course, Speedos aren’t the only undergarment made from spandex. Wouldn’t a pair of bike shorts carry a lower social liability if people find out you’re wearing them? Maybe, but the longer legs and higher waist are, for me at least, less comfortable during non-cycling activities. In warmer weather, layering spandex under pants or shorts can also quickly get too hot, something the minimal cut of a Speedo helps prevent.

I read that article about Guantanamo over a decade ago, back when we all still thought George Bush was the worst President the U.S. ever had. And a Speedo has been my go-to underwear in the outdoors ever since. Heck, they last so long, I’ve still got a pair or two that date back to that time. I’ve worn them while skiing in frigid temperatures, under a pair of shorts while exploring a very humid Havana, and even under my wetsuit, where a Speedo makes the contortions necessary to pull one of those off on a beach a hell of a lot less embarrassing. They’re good for a few solid days of wear, but if one does get stinky, a quick plunge into water will get it clean, and it’ll be dry after your wring it out. In all that time I’ve never experienced chaffing, never twisted anything that didn’t want to be twisted, and never been repulsed by my own odor. They layer well, too: any combination of base layers and pants you can come up with just slides right over the smooth spandex. 

Is all this a little embarrassing? Yes. Is the comfort a Speedo offers worth it? Totally. 

Buy Now

More IndefinitelyWild