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Smartwool Merino 150 Bikini Review

Comfortable, light, and breathable, making it a good partner on lightweight adventures
Smartwool Merino 150 Bikini
Photo: Smartwool
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Price:  $30 List | $30.00 at REI
Compare prices at 3 resellers
Pros:  Super comfortable, quick to dry, lightweight, breathable
Cons:  Tight waistband, more expensive
Manufacturer:   Smartwool
By Lauren DeLaunay & Trish Matheny  ⋅  Jul 13, 2021
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76
OVERALL
SCORE


RANKED
#5 of 13
  • Comfort - 35% 7
  • Fit - 30% 7
  • Drying Time - 25% 9
  • Packability - 10% 8

Our Verdict

While the Smartwool Merino 150 Bikini certainly threw down some competitive performance because of its comfortable material, fast drying time, and low weight, we were disappointed in the waistband, which could use more stretch to make it easier to put on and take off. Featuring a soft and comfortable merino blended fabric, we loved how well these undies were able to breathe during activity and efficiently wick moisture away from our body during intense heat or activity. However, due to a lower score in the important fit metric, it didn't quite measure up next to our favorite merino wool product.

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Price $30.00 at REI
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Pros Super comfortable, quick to dry, lightweight, breathableSilky fabric, stays in place, cute design, breathability, bonded seams prevent chafing and panty lines, quick dryingMost comfortable fabric, well-constructed design, quick drying, true to sizeLightweight, quick-drying, merino woolInexpensive, soft, quick-drying, no bulky seams
Cons Tight waistband, more expensiveExpensive, runs largeExpensive, heaviest thong testedLess practical fit, expensiveImperfect fit for some
Bottom Line Comfortable, light, and breathable, making it a good partner on lightweight adventuresSuper comfortable, breathable, and a flattering fit that allows you to forget about your undies and focus on your adventureThis exceptional thong-cut garment is a super comfortable, well-designed product that excels in urban and backcountry travelThis is a high quality, flattering, and super comfortable bikini-cut model made out of quick drying and soft merino woolSoft, stretchy, and quick to dry, this value-forward garment won us over without making us pay a high price
Rating Categories Smartwool Merino 15... ExOfficio Modern Bi... Icebreaker Siren Thong Icebreaker Siren Bi... Under Armour Pure S...
Comfort (35%)
7.0
9.0
9.0
9.0
7.0
Fit (30%)
7.0
9.0
9.0
8.0
5.0
Drying Time (25%)
9.0
9.0
8.0
8.0
9.0
Packability (10%)
8.0
8.0
7.0
8.0
8.0
Specs Smartwool Merino 15... ExOfficio Modern Bi... Icebreaker Siren Thong Icebreaker Siren Bi... Under Armour Pure S...
Material 87% Merino Wool, 13% Nylon Core 82% Nylon, 18% Spandex 83% Merino Wool, 12% Nylon, 5% Lycra Spandex 83% Merino Wool, 12% Nylon, 5% Lycra 68% Nylon, 32% Elastane
Measured Weight (oz) 0.7 oz (S) .8 oz (S) .9 oz (M) 1.1 oz (S) 0.7 oz (S)
Flat-lock Seams Yes Seamless Yes No Seamless
Cut Tested Bikini Bikini Thong Bikini Hipster
Cuts Available Bikini Bikini Thong, bikini, hipster Bikini, thong Hipster, cheeky, thong

Our Analysis and Test Results

While the Merino 150 Bikini is impressively soft and lightweight, and its merino wool fabric makes for a naturally odor-free and fast-drying product, we were disappointed by the fit of the waistband and would rather pack another wool option for more control and less adjusting during our next backcountry adventure.

Performance Comparison


The warm sunshine of Bishop, California is a great place to test the...
The warm sunshine of Bishop, California is a great place to test the Merino 150 Bikini!
Photo: Lauren DeLaunay

Comfort


What good is underwear if it's not comfy? 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 its limits.

These undies scored well in this category because of their thin and lightweight merino wool construction. We found it to be quite 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 Bikini felt weightless and smooth.

The merino wool of the Merino 150 Bikini is silky smooth and super...
The merino wool of the Merino 150 Bikini is silky smooth and super soft.
Photo: Lauren DeLaunay

In addition to its silky smoothness, we loved that the Merino 150 Bikini kept us dry and cool. We found incredible breathability with this product, which becomes increasingly important the longer we stayed in the backcountry. The wool offers a noticeably different feel when compared to the synthetic nylon blended options available and we loved that the comfort offered by this pair of undies left us feeling luxurious and fresh.

Fit


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.

In general, we were satisfied by 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 Bikini left a lot to be desired.

Despite the tight waistband, we enjoyed the modest yet cute fit of...
Despite the tight waistband, we enjoyed the modest yet cute fit of the Merino 150.
Photo: Lauren DeLaunay

Drying Time


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 need to know that our underwear will dry incredibly quickly on our bodies, which is crucial when you have a full day of action ahead of you. We soaked these undies in a bucket of water alongside all of their competitors, wrung them out by hand, and hung them on a line to dry and these are our results. On a beautiful California day with 9% humidity and a light breeze, the Merino 150 Bikini was dry in about 45 minutes. The fastest pairs dried in roughly 30 minutes.

The Merino 150 Bikini blowing in the breeze in Bishop, California.
The Merino 150 Bikini blowing in the breeze in Bishop, California.
Photo: Lauren DeLaunay

Packability


We know your space is a precious thing. Backpacking, traveling, or just trying to downsize? All that being said, we should also point out that the difference between our lightest (thongs) and heaviest products (hipkinis) 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.

At just 0.7 ounces, this is 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.
Photo: Lauren DeLaunay

Value


The Merino 150 Bikini is priced square in the middle of the many products we tested. For a more expensive price tag, we were hoping for a better fit. While we found far superior wool garments available for a slightly more expensive price, if you're on a tight budget, it's possible to get many (though not all) of the same benefits with the Merino 150 Bikini while saving a few bucks.

Conclusion


If it weren't for the tight waistband, we'd be completely in love with this product. The Smartwool Merino 150 Bikini is constructed out of a comfortable merino wool blend, breathable, and exceptionally light. This is a perfectly fine pair of underwear, but a few other models performed a touch better across the board.

A good pair of travel underwear, the Merino 150 Bikini has no...
A good pair of travel underwear, the Merino 150 Bikini has no crucial flaws. We only have a rather minor wish that the waistband had more stretch to it.
Photo: Lauren DeLaunay

Lauren DeLaunay & Trish Matheny