The Best Women’s Active Underwear

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The best underwear is the kind you don’t notice. When you do, it’s probably not doing its job. Finding out mid-run or mid-hike that your underwear just won’t stay in place sucks. A literal pain in the butt. So with help from four other testers, who wear sizes extra small to large, I set out to find the best options for spending time outdoors. We tried 20 pairs of underwear—hipsters, bikinis, boy shorts, cheekies, and thongs—from nine different outdoor brands. All promised to be the ultimate you’ll-never-go-back underwear. After three months of hiking, climbing, running, and hanging out, Icebreaker’s Sprite Hot Pant is the winner.

Icebreaker’s ultralight wool underwear topped our lists for its comfort, fit, odor control, and style—the material was a top choice for every member of the test team. Testers had different cut and fit preferences, but the overall favorite pair was the Sprite Hot Pant, an 83 percent merino wool, 12 percent nylon, and 5 percent Lycra blend cut in a boy-short style.

I tested the Sprite Hot Pant on a six-day backpacking trip in Jordan, with temps in the 80s and 90s and full sun. I never found myself thinking about my underwear while I was wearing them, andmy crotch and butt never felt sweaty. Until this test, I’ve always been more of a brief and bikini kind of person, but these (and a few other styles we’ll get into later) have turned me on to boy shorts.

Full coverage isn’t for everyone, and it’s not always the best to wear under tight clothing. But for a hike, I love how I don’t have tug on wedgies in between scrambles. I also never had to worry about them falling down—which has probably happened to you if you’ve ever accidentally paired two incompatible fabrics. The waistband is tight but, in my opinion, not uncomfortably so. However, another size-medium tester felt the band nearly “cut my body in half and made it seem like I had a roll where I don’t.” She preferred Icebreaker’s other styles instead.

The Siren Bikini ($30) andSiren Thong ($28)use the same 83 percent merino wool, 12 percent nylon, and 5 percent Lycra fabric. If you’re not into boy shorts, check out one of those instead.

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Perhaps surprisingly, given cotton’s bad rap in performance wear, Kari Traa’s Attraktiv Hipster, a 95 percent cotton, 5 percent elastane blend, was a close second favorite. Once I tore off the tags, I found these to be the most comfortable of all the pairs I tried. They fit like shorts and rarely ride up, even during high-output activities. “They fit perfectly under spandex shorts and they don’t move,” one tester said.

The Attraktivs made me re-evaluate my aversion to cotton. I wore them on a trail hike in Jordan and didn’t notice them at all during the day. Another tester observed the same thing. “There’s enough fabric that they can be worn comfortably without pants”—such as around the house, or when you’re changing around other people and want full coverage—“but not so much that it feels like you’re wearing shorts under your pants,” she said. 

Testers also loved this pair for yoga. “It didn’t restrict my range of motion at all,” said one tester, in spite of the full-coverage fit that puts more fabric in your hip crease than a thong or high-cut bikini.

The downside, however, is that they don’t dry quickly. I loved this underwear so much that I tried to wash them in the sink at my hotel to wear them again, but it’s not a fast process. They’re hands-down my choice for comfortable, don’t-even-feel-’em underwear, but they’re not the best pick for travel or backpacking—or for activities where you’re going to work up a huge sweat and won’t be able to change quickly afterward.

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ExOfficiohas made a name for itself with its ultra-quick-dry underwear, made from 93 percent nylon and 7 percent Lycra spandex. Its Sport Mesh Bikini Brief—also available in other cuts—is my top choice for travel. Even for a monthlong trip, three or four pairs of ExOfficio underwear are all you need. Maybe just two, if you’re ambitious. A quick wash in the sink with any kind of soap cleans them up in a jiff, and they essentially dry in minutes if you wring them out well, lay them flat on a towel, roll it up, and stomp on it a bit.

Many times, I have put on the Sport Mesh shortly after this routine, slightly damp, and they’ve dried out on my body underneath my clothes. One tester who’s long worn this model says it’s hands-down her favorite pair of underwear for all activities—running, hiking, yoga, and especially multi-day climbing and backpacking trips. “They bunch sometimes while running, but they don’t chafe, so it’s not a problem,” she says.

I’m not a runner or climber, but I can vouch for ExOfficio’s Sport Mesh undies for hiking and backpacking. They wick moisture exceptionally well, and you won’t feel the need to change immediately even after working up a sweat. And they’re a breeze to rinse out and dry in the backcountry. If you’re going on a multi-day backpacking trip, wear a pair and pack a spare—that’s honestly all you’ll need.

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Icebreaker Siren Thong ($25)

Icebreaker’s Siren Thong feels great. A tester who frequently wears them ran a half-marathon inthe Siren Thongand said it was the “most comfortable” she’s ever worn. The fabric is soft and just stretchy enough that it won’t pull in uncomfortable ways, so it feels like the best cotton underwear while wicking moisture like wool. 

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Each woman who tested underwear for this review had a different favorite pair and a different pair that’s now her last-resort, laundry-day underwear. Not only are we different shapes and sizes, we all do different activities, and it’s hard to define “performance” across the board. What’s great for yoga isn’t always great for running, and even the best hiking underwear might not be what you want to sleep in. Here are a few other pairs that got mixed reviews but which may be worth looking into.

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Testers liked both of these pairs for their quick-dry, moisture-wicking capabilities and ability to stay in place well. However, feelings were mixed about the two different cuts and what they’re best for. The Active Brief, in particular, is extremely thin and offers a “barely there” feeling. Once, while wearing them, I had a sudden pang of worry that I had accidentally gone commando.

One tester said the Active Brief stayed in place well for running, unlike almost every other pair she’s tried in the past, but that the leg holes were too tight on her thighs and she couldn’t comfortably wear them all day. Another said she loved the Boy Shorts for almost every activity—especially climbing, yoga, hiking, and everyday wear—but not for running because of an awkwardly placed seam in the crotch that chafes. And a third appreciated the barely-there feel of the Active Mesh Boy Shorts but thought they were cut too long—they hung out of the bottom of her spandex shorts.

Reviews of Smartwool’s underwear, a blend of merino wool, polyester, nylon, and lycra, were mixed. One tester thought they were too hot and itchy at first but noticed they felt better after more washes and wears. The bikini stayed in place well during lifting and cross-training but was too heavy for comfort, she said—it would be better suited for colder weather. We’ll keep testing them and reevaluate later on this year.

I thought the bikini fit and stayed in place well, but it and the boy shorts were too high-waisted and didn’t want to stay put. Both have tight waistbands that, while not uncomfortable, made the flesh at my hips bunch into unflattering lines. The boy shorts were almost impossible to wear under tight pants—the stretchy fabric rolled up and bunched. I was often pulling them down.

Our testers either loved or hated Craft’s Greatness Brazilian underwear. They’re ultralight, and when they stay in place it’s almost as if they’re not there. However, the fit is quite cheeky. “The first day I wore them, I didn’t realize I was wearing underwear all day,” one tester says. “It was a feeling I’ve never experienced.” But while doing squats, she and another tester noted that they rode up. And I found them to ride up even while just walking a few blocks. These are a good example of a style for which comfort varies significantly from one person to the next.

Ortovox’s Ultra Hot Pants wear almost like boxer shorts. The 105-gram pair is 85 percent merino and 15 percent polyamide. I found they got quite sweaty while riding a cruiser bike in jeans on a cool yet humid morning by the beach, but they were comfortable for hiking and everyday wear (except for under tight-fitting clothes like skinny jeans).

With five women trying more than a dozen pairs of underwear, we had a lot of different opinions. We weren’t able to get enough samples for every woman to try every pair—in some cases, sizes or styles were back-ordered—but with one exception (the Ortovox 105-gram Ultra Hot Pants), every pair was tried by at least two or three women. I interviewed every woman who tested models for this review about the activities she did while wearing them, how they performed, and which pairs she gravitated toward when she wasn’t explicitly thinking about testing.

Icebreaker’s ultralight wool undies won out because of consistency. Of all the pairs we tried, Icebreaker’s merino blends garnered the most consistent positive feedback. Despite style preferences, reviews of Icebreaker’s underwear were excellent across the board.

Five active women, who wear sizes extra small to large, had drastically different opinions about each pair of underwear. You likely will too—it’s the most personal piece of clothing you wear, perhaps even more than your bra. And since it’s the one piece of clothing you can’t try on before you buy, and often something you can’t return, buying can be tricky. Especially since high-quality pairs aren’t cheap. Here’s how I recommend shopping:

 Sizing was wildly inconsistent. One tester who usually wears size medium needed to size up to a large for some pairs, and one tester who usually wears a large needed to size down in others. Take time to take your measurements and make sure they’re right, and match them up with the sizing charts on brands’ websites. In stores, ask for help, and online, call customer service for recommendations if you seem to be between sizes and aren’t sure whether to go up or down. ExOfficio, for example, lists a phone number for sizing help on its website, and Backcountry.com has a team of Gearheads at the ready to talk you through any purchase. Ask about return policies too. Often underwear can’t be returned, even if it’s unworn, but some stores have exceptions for products that don’t work out.

This test taught us not to underestimate the psychological importance of a well-fitting pair of underwear: we liked pairs that we felt made us look good. When a pair dug into our skin in an unsightly way or was highly visible under clothing, it was hard to separate aesthetics from performance benefits.

As an all-purpose fabric, wool is as good as it gets. We liked it for hiking, backpacking, running, weightlifting, backcountry skiing, cross-training, sleeping, and kicking around. It wicks moisture exceptionally well, dries quickly, and repels odors. Take a close look at fabric blends, however. Icebreaker’s 83 percent merino underwear wore and performed quite differently from Smartwool’s 68 percent merino, 20 percent polyester underwear. Otherwise, if drying fast is your main concern, you probably want mesh nylon underwear, like ExOfficio’s. And of course cotton has its place too, especially for everyday wear.

Even the best fabric is useless if the style irks you. If you’re thinking about your underwear instead of the gorgeous trail you’re hiking, it’s not a good fit. Take stock of what you already own. Which pairs ride up when you do squats, and which have you picking wedgies in the middle of the night? Which pairs do you gravitate toward first after doing laundry, and which do you wear as punishment for not doing laundry sooner? Lay them out in a stack to see size differences—maybe sizing up or down would do you good—and look at the fabric blend listed on the tag (or on the company’s website, if you cut out the tags long ago). See if you can find a trend. Is it the size? Shape? Fabric? Pick out a couple of characteristics you’d have in an ideal pair of underwear, then go from there.