Updated 06/10/2026

BRANWYN’s seamless merino wool underwear and bras offer soft comfort with effective moisture management and odor resistance, making them a strong choice for outdoor activities.

BRANWYN merino wool underwear and bras have become my go-to choice for outdoor activities. What stands out most is how consistently they perform through long days of movement, staying steady through moisture and changing conditions without needing constant adjustment. Even on warmer outings, they hold up well against irritation and remain comfortable against the skin. And while I can sometimes be sensitive to wool, I’ve never found these to be itchy.

Why Merino Wool Works So Well for Underwear

Merino wool performs differently than most synthetic fabrics used in active underwear, particularly in how it handles moisture and odor during activity.

It naturally regulates temperature across changing conditions while absorbing moisture into the fiber structure rather than pushing it outward. This helps the fabric feel more comfortable against the skin during sustained activity.

Odor resistance is another major advantage, especially on multi-day trips. Synthetic fabrics tend to trap odors quickly, while merino wool naturally stays fresher much longer. I’ve personally noticed a huge difference in odor retention compared to other brands of underwear.

The fabric also holds its shape very well over time. Even after regular use, my BRANWYN pieces still feel supportive and haven’t stretched out the way some synthetic underwear eventually does.

BRANWYN Essential Bralette

In general, I’ve found that many active bras feel more restrictive than I prefer, especially for hiking. I’m a smaller person and don’t need much compression, so I tend to look for bras that prioritize comfort and ease of wear over high support. I’m also prone to skin irritation and rashes under bra bands, so moisture management and a softer, more forgiving fit are especially important for me.

This bra provides solid support for a low-impact style and has a wide bottom band that stays put better than most bras I’ve used during hiking and other active days. The straps are convertible, so you can wear them straight or switch to a cross-back depending on fit and comfort, which I appreciate for dialing in support. The fit runs small in my experience, so I recommend sizing up — especially if you prefer a looser bottom band like I do. I sized up to a large (even though I normally wear a small), and that size works perfectly for me.

Overall, this is the best bra I’ve used for hiking and backpacking.

• fabric: 81% extra fine merino wool, 14% nylon, and 5% elastane
• price: $52

BRANWYN Essential Hipster

The hipster is a my favorite style for providing good coverage, with a higher rise and wide waistband that doesn’t shift around or need adjustment during activity.

• fabric: 81% extra fine merino wool, 14% nylon, and 5% elastane
• price: $40

BRANWYN Essential Boyshort

The boyshort offers more coverage than the hipster, but still moves easily without feeling bulky. What I like most is how adjustable the fit feels depending on how you wear it — lower on the hips or pulled higher depending on preference and activity. Either way, it stays in place well without rolling, digging in, or shifting during movement. Even with the fuller coverage, it still has a streamlined, flattering fit.

• fabric: 81% extra fine merino wool, 14% nylon, and 5% elastane
• price: $42

BRANWYN Essential Bikini

The bikini style offers a lower-profile fit while still maintaining more coverage than many standard bikini cuts. It’s a good option if you prefer something lighter and less coverage overall. It also stays in place well during activity — and has held up well over time with regular use, maintaining its shape and comfort even after a year of wear.

• fabric: 81% extra fine merino wool, 14% nylon, and 5% elastane
• price: $38

What Makes BRANWYN Different

I recently had the opportunity to join a call with BRANWYN CEO Deanne Buck, where she shared more about the company’s mission, materials, and approach to product design.

BRANWYN was created because its original founder struggled to find natural fiber underwear that worked well for active use. At the time, most performance underwear options were heavily focused on synthetic materials like nylon and polyester. The company was built around the idea that women deserved better next-to-skin clothing designed specifically for active lifestyles.

The company also intentionally focuses only on women’s products. BRANWYN views these as intimate products and wants to create a space specifically centered around women’s comfort, performance, and experiences outdoors. That focus comes through clearly in both the design and fit of the products.

One of the biggest differences with BRANWYN is the seamless merino wool construction. Instead of creating fabric first and then cutting and sewing garments together, the products are knit into their final shape at the same time the fabric itself is made. This helps the garments maintain their shape well over time while also eliminating bulky seams that can become uncomfortable during long hikes or active days.

BRANWYN also uses a higher percentage of merino wool than many similar products. Most of BRANWYN’s products use about 80% merino wool, compared to lower wool percentages often found in synthetic-heavy blends. During the call, Deanne explained that using higher wool content is much more difficult during manufacturing because wool shrinks during the dyeing process and creates more wear on the knitting equipment. But maintaining that higher wool percentage is important to the company because it improves fabric performance.

Sustainability and Company Values

Another thing I appreciate about BRANWYN is how much thought the company puts into sustainability and product impact.

Their philosophy isn’t simply to “do less harm,” but to actively make better choices throughout the production process. The wool fibers themselves are biodegradable, and the company uses compostable and recyclable packaging instead of traditional plastic packaging whenever possible. Products are also certified OEKO-TEX Standard 100, which means the materials have been tested for harmful substances, and Woolmark certified, which verifies the quality and authenticity of the wool.

BRANWYN is also certified PFAS- and BPA-free and works closely with Textile Exchange while continuing to explore more biodegradable and recycled material options for components like nylon and elastane.

I also appreciate that BRANWYN approaches sustainability as an ongoing process rather than a marketing feature. During the call, Deanne mentioned that the company won’t bring something into the world without considering the impact it will have, which feels consistent with the materials, packaging, and overall design philosophy behind the brand.

Gear Reviews: My goal is to share clear, unbiased information about outdoor gear. I am not sponsored by any gear companies and I don’t accept paid posts or links. I regularly receive products from brands for review, with no expectation of a positive review and no compensation for my opinions. As an independent gear reviewer, I only review items I’ve personally used on multiple trips and that I believe are high-quality and worth recommending.

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