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Icebreaker Siren Bikini Review

This is a high quality, flattering, and super comfortable bikini-cut model made out of quick drying and soft merino wool
Icebreaker Siren Bikini
Photo: Backcountry
Top Pick Award
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Price:  $35 List | $21.00 at Backcountry
Compare prices at 2 resellers
Pros:  Lightweight, quick-drying, merino wool
Cons:  Less practical fit, expensive
Manufacturer:   Icebreaker
By Lauren DeLaunay & Trish Matheny  ⋅  Jul 13, 2021
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84
OVERALL
SCORE


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

Our Verdict

The Icebreaker Siren Bikini is a cute garment great for a wide array of activities. With a mostly wool construction, it's naturally odor-resistant and soft, while the small percentage of Lycra adds a surprising amount of stretch. Our testing team found the bikini cut to be visually flattering and comfortable. At 1.09 ounces, it has an impressively quick trying time for a thicker wool material. After weeks of travel, trail running, and swimming in these undies, we came to appreciate the merino wool blend a lot. We recommend this bikini for anyone who prefers to wear natural wool fabrics over synthetic ones, or anyone specifically seeking a pair that can be worn for multiple days without building up an odor.

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Pros Lightweight, quick-drying, merino woolSilky 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 sizeBreathable, comfortable, inexpensiveInexpensive, soft, quick-drying, no bulky seams
Cons Less practical fit, expensiveExpensive, runs largeExpensive, heaviest thong testedTight fitImperfect fit for some
Bottom Line This is a high quality, flattering, and super comfortable bikini-cut model made out of quick drying and soft merino woolSuper 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 travelThe Barely Hipster is a super comfortable and affordable product made to stand the heatSoft, stretchy, and quick to dry, this value-forward garment won us over without making us pay a high price
Rating Categories Icebreaker Siren Bi... Modern Travel Bikini Icebreaker Siren Thong Patagonia Barely Hi... Pure Stretch Hipster
Comfort (35%)
9.0
9.0
9.0
8.0
7.0
Fit (30%)
8.0
9.0
9.0
9.0
5.0
Drying Time (25%)
8.0
9.0
8.0
8.0
9.0
Packability (10%)
8.0
8.0
7.0
7.0
8.0
Specs Icebreaker Siren Bi... Modern Travel Bikini Icebreaker Siren Thong Patagonia Barely Hi... Pure Stretch Hipster
Material 83% Merino Wool, 12% Nylon, 5% Lycra 82% Nylon, 18% Spandex 83% Merino Wool, 12% Nylon, 5% Lycra Spandex 89% Nylon, 11% Spandex 68% Nylon, 32% Elastane
Measured Weight (oz) 1.1 oz (S) .8 oz (S) .9 oz (M) 0.8 oz (S) 0.7 oz (S)
Flat-lock Seams No Seamless Yes Seamless Seamless
Cut Tested Bikini Bikini Thong Hipster Hipster
Cuts Available Bikini, thong Bikini Thong, bikini, hipster Hipster, bikini, thong Hipster, cheeky, thong

Our Analysis and Test Results

The Icebreaker Siren Bikini has a simple, sleek design and is an effective piece of travel underwear that is comfortable, quick-drying, and breathable. It was important for us to test both synthetic and wool base layers for this review and we were blown away by the corespun merino blend that allowed our bodies to move and breathe without needing to adjust. Compared to the others in its class, the Siren Bikini sets the bar for effortless activewear through outstanding comfort, great fit, packability, and a fairly fast drying time despite a thicker wool blended material.

Performance Comparison


The Icebreaker Siren drying quickly in the Patagonian breeze.
The Icebreaker Siren drying quickly in the Patagonian breeze.
Photo: Lauren DeLaunay

Comfort


We all like different fits and cuts, but our testing team worked hard to describe certain characteristics that would help all buyers make the most informed decisions. "Comfort," as we've defined it, refers to each product's next-to-skin feel, material thickness, and breathability.

The Siren Bikini is incredibly comfortable and has a noticeably softer and organic next to skin feel when compared to both its synthetic and wool counterparts. Known for its breathability and moisture-wicking capabilities, this product is 83% merino wool, 12% nylon, and 5% Lycra, and isn't itchy like you might expect from wool.

The austral summer sun illuminates the soft, stretchy wool of the...
The austral summer sun illuminates the soft, stretchy wool of the Icebreaker Siren.
Photo: Lauren DeLaunay

Our team enjoyed the thin material of the Siren Bikini, which led to great breathability and a decent feeling of wearing nothing at all. We like the thin waistband made of soft, simple nylon, and gave this bikini high scores for staying in place during activity. If you're after a high-quality pair of undies that are comfortable and made out of odor-resistant merino wool, this bikini does not disappoint.

Fit


Fit, while closely linked to comfort, deserves its own category. We realized pretty quickly during this testing process that there is one key question we could use to steer our scoring: how much does each pair of undies make it feel like wearing nothing at all? No one wants to spend energy while traveling fussing over underwear, so we identified the following traits to help us guide the "fit" section of this review: shape and cut, stretch, stability, and seams.

The waistband of the Siren stretches easily for taking off and...
The waistband of the Siren stretches easily for taking off and putting on. One tester felt that the leg openings could be a bit wider, but other testers found the snug thigh fit to be a non-issue.
Photo: Lauren DeLaunay

Another great thing about the Siren Bikini is the stretch. We were truly impressed by the elasticity, and we never felt held back by its fabric. Another thing we approved of is its "stability," — our nice way of saying that we never got any wedgies while wearing this product. The leg openings might be a bit tight, but forced to choose between a little bit snug or constant wedgies, we'd definitely choose snug.

Drying Time


Drying time is a pretty simple concept in underwear testing, but each product's score tells us two things: how dry will I stay when sweating, and how quickly will my clothing air dry? For this test category, we hung all the products on clotheslines after washing and soaking completely, and we also recorded our experiences hiking in hot, humid places.

The Siren Bikini is competitive here, and while it isn't the single fastest, it was nearly as close as some of the thinner synthetic models we tested. Hanging on a line to dry in southern Chile as well as in the Tetons, we were impressed that with just an hour to spare, we could easily wash these undies, dry them, and get right back to the action.

Washing laundry in Cochamo would be easier if all our clothes dried...
Washing laundry in Cochamo would be easier if all our clothes dried as fast as the Icebreaker Siren!
Photo: Lauren DeLaunay

One thing we noticed, both while washing and while sweating, is that the corespun merino wool material of the Siren Bikini does a great job fending off excess moisture. While some synthetic products both soak up water and dry out quickly, the wool seems to wick moisture away from the body. While this doesn't apply to washing, it does apply to hiking, running, and traveling in hot, humid environments. The Siren Bikini may not be the fastest to dry when compared to other merino wool options available, however, we found that it was still our preferred wool option when packing for adventures on the road.

Packability


We want to know how much room each product takes up in our pack by both measuring its weight and evaluating its three-dimensional space.

Weighing the Icebreaker Siren to get an accurate read on packability
Weighing the Icebreaker Siren to get an accurate read on packability
Photo: Lauren DeLaunay

As with many of the other underwear models that we tested, the Siren Bikini takes up practically no room at all. Even though it is one of the heavier models that we tested, weighing 1.09 ounces, we loved having this garment with us on long backpacking trips, and as people who are routinely pushing the limits of airline baggage, our suitcases thanked us too. Compared to other models, especially synthetic models, these don't pack down as small though. If you're packing several pairs of underwear, the space required adds up. However, being naturally odor-resistant, you might be more likely to pack fewer pairs of underwear on a trip than you might if wearing synthetic models.

Value


As a merino wool product, the Siren Bikini is one of the more expensive products we tested for this review and we are confident you will not regret investing those hard-earned dollars. We love this well-designed garment, featuring a more stylish bikini cut, and effortless performance due to its merino blend technology. While our review features more affordable synthetic options, they simply do not match the high-quality, well-constructed design of the Siren.

Conclusion


The Icebreaker Siren Bikini has an impressively soft next-to-skin feel built with merino corespun technology that kept us dry and comfortable no matter how quickly we were moving through the mountains. This bikini is an outstanding wool option.

The Icebreaker Siren was a great addition to our backcountry...
The Icebreaker Siren was a great addition to our backcountry adventure thanks to its quick drying time and soft material.
Photo: Lauren DeLaunay

Lauren DeLaunay & Trish Matheny