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Smartwool Merino 150 Bikini Review

Comfortable, light, and quick to dry, making it an excellent partner lightweight adventures
Top Pick Award
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Price:  $30 List | $24.00 at Amazon
Compare prices at 3 resellers
Pros:  Super comfortable, quick to dry, lightweight
Cons:  Tight waistband, more expensive
Manufacturer:   Smartwool
By Lauren DeLaunay ⋅ Senior Review Editor  ⋅  Apr 26, 2018
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#4 of 9
  • Comfort - 35% 7
  • Fit - 30% 7
  • Drying Time - 25% 9
  • Packability - 10% 9

Our Verdict

The moment we took the Smartwool Merino 150 Bikini out of its packaging, we knew we had a winner. The longer we tested it, the more we loved it, and we had no problem awarding it our Top Pick Award for Best Wool Product. We loved its soft material, modest yet cute cut, fast drying time, and low weight. What more could we ask for? With knockout scores across the board, we never wanted to take these undies off. The only issue we had was with the waistband elasticity, which could lead us to a stretchier product.

Color Updates

The shade of purple we tested is no longer available, but check out a current offering from Smartwool in the image above.

April 2019

Compare to Similar Products

Our Analysis and Test Results

The Merino 150 Bikini is impressively soft and lightweight, and its merino construction makes for a naturally odor-free and fast-drying product. As our Top Pick for Wool, we loved how fresh and dry we stayed no matter how fast we were moving through the mountains. With super-soft material and a modest yet cute cut, we never wanted to take these undies off!

Performance Comparison

The warm sunshine of Bishop  California is a great place to test the Merino 150 Bikini!
The warm sunshine of Bishop, California is a great place to test the Merino 150 Bikini!


What good is underwear if it's not comfy? Here at OutdoorGearLab, we know that comfort is critical to success, whether you're deep in the backcountry or on a 17-hour flight across the Pacific, which is why we made this our very first scoring metric. For this category, we evaluated all things material: softness, itchiness, breathability, thickness, you name it. Our testers spent weeks hiking, climbing, running, and traveling in this underwear to truly test their limits, and results are in.

And hello, softness! The thin, lightweight merino wool of the Merino 150 Bikini was without a doubt one of our favorite materials. We found it to be exquisitely soft next to our skin, passing our first big test of travel underwear: forgetting we even have them on. Whether you're running to catch a bus or racking up miles on the track, the thin material of the Merino 150 felt weightless and smooth.

The merino wool of Smartwool's Merino 150 Bikini is silky smooth and super soft.
The merino wool of Smartwool's Merino 150 Bikini is silky smooth and super soft.

In addition to its silky smoothness, we loved that the Merino 150 kept us dry and cool. We found incredible breathability with this product, which becomes increasingly important the longer we stayed in the backcountry. Our other favorites for this metric were the Patagonia Barely Hipster, whose thin polyester was incredibly breathable, and the ExOfficio Give-N-Go Sport Mesh Hipkini whose nylon/Lycra blend felt luxurious and fresh.


Even though "fit" is closely linked to "comfort," we had to divide these metrics up into two categories so we could adequately describe all the ways these undies felt on our bodies.

For this metric, we looked to cut, stability, and stretchiness to give us an idea of how the products helped or hindered our range of motion.

Despite the tight waistband  we enjoyed the modest yet cute fit of the Merino 150.
Despite the tight waistband, we enjoyed the modest yet cute fit of the Merino 150.

In general, we liked the cut of the Merino 150 Bikini. We found it to be modest yet flattering, and we appreciated the appropriately-sized leg openings and low-rise waist. However, the most significant problem we had with this product was the waistband's lack of elasticity. We found it to stretch decently once we had it on, but it was difficult to pull on, especially in cramped spaces. Compared to the never-ending stretchiness of some of its competitors, the Merino 150 left something to be desired. This product could have easily been in the running for our top Editors' Choice Award had it not been for this one issue.

Comparatively, our other award winners, the Barely, Give-N-Go, and UA Pure Stretch Hipster, all had incredibly stretchy designs that moved easily no matter what we were doing.

Drying Time

Need to wash your underwear but only have an hour to spare? Have no fear, the Merino 150 Bikini is here! We soaked these undies in a bucket of water alongside all of its competitors, wrung them out by hand, and hung them on a line to dry.

On a beautiful California day with 9% humidity and a light breeze, the Merino 150 Bikini was dry in about 45 minutes. We loved knowing that we could wash and wear these again in a pinch, whether we're traveling through South America or on an extended backcountry ski trip.

The Smartwool Merino 150 Bikini blowing in the breeze in Bishop  California
The Smartwool Merino 150 Bikini blowing in the breeze in Bishop, California

The drying time of a product is as crucial for washing potential as it is for breathability and comfort. If we work up a sweat, we know that the Merino 150 will dry incredibly quickly on our bodies, which is crucial when you have a full day of action ahead of you. These undies dried twice as fast as some of the other products we tested, and we appreciated all the time we saved.


Here at OutdoorGearLab, we know your space is a precious thing. Backpacking, traveling, or just trying to downsize? The Merino 150 has your back.

At just .7 oz, this was one of the lightest products we tested and was about half the weight of the heaviest undies in this review. Its thin material also aids in its packability, letting you shove it into tight corners and spaces in your pack.

Teeny tiny! The Merino 150 is thinner than a standard carabiner.
Teeny tiny! The Merino 150 is thinner than a standard carabiner.

All that being said, we should also point out that the difference between our lightest and heaviest products was not much more than half an ounce, so we recommend using this metric as a secondary test after picking based on more important properties like the ones described above.


The Merino 150 Bikini is priced square in the middle of the many products we tested. For such high quality, we have no problem shelling out the cash for this great product, which we see as an investment in our backcountry and travel comfort. However, if you're on a tight budget, it's possible to get many (though not all) of the same benefits while saving a few bucks.


If it weren't for the tight waistband, we'd be completely in love with this product. The Merino 150 Bikini from Smartwool is comfortable, breathable, and exceptionally light. We knew it was award-worthy, so we crowned it our Top Pick for Wool! The material is luxuriously soft and thin, though we will issue one final warning: our testers had no problems with durability while testing this product, but merino is notoriously delicate. If you plan to get rowdy in your undies (hey, we don't judge), you may want to look for a synthetic material.

Our Top Pick Wool: the Smartwool Merino 150 Bikini!
Our Top Pick Wool: the Smartwool Merino 150 Bikini!

Lauren DeLaunay