6 Best Merino Wool Briefs For Cold Weather Backpacking That Keep You Dry
Stay warm and dry on cold trails. We review the top 6 merino wool briefs for backpacking, focusing on moisture-wicking and odor-resistant comfort.
It’s 6 a.m. in a frosty tent, miles from the nearest trailhead, and the thought of putting on yesterday’s cold, clammy underwear is almost enough to keep you in your sleeping bag. We’ve all been there, where a small gear choice makes a huge difference in morale and comfort. Choosing the right baselayer, starting with your briefs, is the first step to staying warm, dry, and focused on the adventure.
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Why Merino Wool is Essential for Cold Weather
When the temperature drops and you’re working hard on the trail, managing moisture becomes your number one job. This is where merino wool truly shines, leaving cotton and even some synthetics in the dust. Unlike cotton, which absorbs moisture and holds it against your skin, merino wool actively pulls sweat vapor away from your body before it even turns to liquid, a process called wicking.
The magic doesn’t stop there. Merino fibers can absorb up to 30% of their own weight in moisture without feeling wet to the touch. This means that even when you’re sweating on a steep ascent, the fabric keeps that clammy feeling at bay. Critically, wool insulates even when it’s damp, providing a vital thermal buffer that synthetics struggle to match. It’s also naturally odor-resistant, a benefit your tent-mate will appreciate on day three of a trip.
Smartwool Merino 150 for All-Day Comfort
Picture a long day of rolling hills in the shoulder season, where you’re constantly adjusting layers. The Smartwool Merino 150 is the dependable foundation for exactly these kinds of trips. It’s built for comfort, with an exceptionally soft feel and flatlock seams designed to disappear under a pack’s hip belt, preventing chafing over long miles.
This brief uses a core-spun technology, wrapping soft merino wool around a durable nylon core. This gives you the best of both worlds: the next-to-skin comfort and performance of merino with the added strength and longevity of nylon. For weekend backpackers and seasoned trekkers alike, the Merino 150 is a fantastic, no-fuss choice that simply works.
Icebreaker Anatomica for Unmatched Breathability
You’re snowshoeing up a steep, protected slope, generating a ton of heat, but you know the windy, exposed ridgeline is just ahead. The Icebreaker Anatomica is made for these high-output, stop-and-go scenarios. Its corespun fabric and lightweight construction make it one of the most breathable options available, dumping heat and moisture with impressive efficiency.
The "Anatomica" name points to its fit—it’s contoured and supportive without being restrictive, which is key for dynamic movement. This focus on fit and breathability makes it a top contender for backcountry skiing, winter running, or any activity where you anticipate periods of intense effort followed by static moments in the cold. It helps you stay dry from the inside out, which is half the battle.
Ridge Merino Journey: Durability on the Trail
If you measure your trips in weeks or months instead of days, gear durability moves from a "nice-to-have" to a "must-have." The Ridge Merino Journey brief is engineered for the long haul. While pure merino can be susceptible to wear and tear, Ridge uses its (m)Force™ Technology, wrapping merino around a nylon filament to create a significantly stronger yarn.
This is the brief you choose for a thru-hike of the Appalachian Trail or a rugged traverse of the Wind River Range. It provides all the thermal and anti-odor benefits of merino but won’t give up on you after a few dozen days of hard use and trail-side laundry. It’s a true workhorse, built to withstand the abrasion and abuse of a life lived out of a backpack.
Minus33 Acadian for Its Soft, No-Itch Feel
For some, the mere mention of "wool" brings back memories of scratchy, uncomfortable sweaters. The Minus33 Acadian is here to change that perception. Made from 18.5-micron merino wool, these briefs are exceptionally soft and are an excellent choice for anyone with sensitive skin or a prior aversion to wool.
The microweight fabric provides a touch more substance than some ultralight options, giving it a cozy, comforting feel that’s perfect for a cold night in the tent or lower-output days. Think of it as the comfort food of baselayers. It’s ideal for cold-weather camping, ice fishing, or any adventure where next-to-skin softness is your top priority.
Black Diamond Solution 150 for Alpine Pursuits
When your objective involves a rope, harness, and a healthy dose of adrenaline, your gear needs to perform at another level. The Black Diamond Solution 150 brief is born from this world. It leverages Nuyarn technology, a spinning process that drafts merino fibers around a nylon core in a way that amplifies the wool’s natural performance.
The result is a fabric that is stronger, stretchier, and dries significantly faster than conventional merino. The fit is athletic and purpose-built for movement, staying put under layers during high-steps on an ice climb or kick-turns on a ski tour. This isn’t just underwear; it’s a piece of technical equipment for mountain athletes who demand the most from their baselayer system.
Ortovox 150 Cool for High-Output Activities
Pushing hard on a spring ski tour, you’re often generating summer-level heat despite the freezing air. The Ortovox 150 Cool is designed for this exact paradox. It blends merino wool with Tencel™, a fiber derived from sustainable wood pulp that has a naturally cooling effect on the skin and wicks moisture exceptionally well.
This unique combination makes the 150 Cool perfect for high-pulse activities where you’re likely to overheat. It provides the core benefits of merino—odor control and insulation—while actively working to manage high temperatures during intense effort. For the "fast and light" crowd or anyone who runs hot, this blend offers a tangible performance advantage when you’re pushing your limits.
Choosing Your Briefs: Wool Weight and Fit Guide
Navigating the world of merino can feel complex, but it boils down to two key factors: fabric weight and fit. Most of the briefs listed here are around 150 g/m², which is the industry standard for lightweight, three-season or active-winter use. This weight offers a great balance of warmth, breathability, and low bulk, making it incredibly versatile.
Fit is just as critical. For a baselayer to effectively wick moisture, it needs to be in contact with your skin. You’re looking for a fit that is snug but not restrictive. It should move with you without bunching or sagging. A loose baselayer simply can’t do its job of pulling moisture away from your body, leaving you feeling damp and cold.
When making your final choice, consider the primary tradeoff: pure merino vs. a blend.
- 100% Merino: Often feels slightly softer and offers the absolute best odor resistance. It can be less durable over the long term.
- Merino/Nylon Blends: Significantly increases durability and can speed up drying time. This is the best choice for long-distance backpacking or for anyone who is hard on their gear.
- Merino/Tencel Blends: A specialized option for those who run hot and prioritize cooling during high-output activities.
Ultimately, the choice depends on your personal needs. Are you prioritizing thru-hike durability or weekend comfort? Are you a fast-moving athlete or someone who enjoys a more relaxed pace? Answering those questions will point you to the right pair.
Don’t get paralyzed by the options. Any of these merino briefs will be a massive upgrade from cotton or old synthetic layers. The goal is to find a piece of gear that’s good enough to do its job, so you can forget about it and focus on the view from the summit. Now, pick a pair and plan your next trip.
