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Hands-on Gear Review

Icebreaker Oasis Review

Long Underwear

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Price:   Varies from $62 - $90 online  —  Compare at 3 sellers
Pros:  Comfortable, good warmth for the weight, resists odors, dries quickly, breathes well, attractive styling
Cons:  Expensive, limited durability
Editors' Rating:     
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Manufacturer:   Icebreaker


The 'Icebreaker Oasis' might sound like an oxymoron, but we found some truth to its naming. This long underwear is warm enough for a crow's nest iceberg watch in the North Atlantic, yet breathable enough to wear while riding a camel in search of a Saharan date palm watering hole (on a cold desert night maybe). Unfortunately, due to the limited structure of our award system it did not take home any prizes, although, it came awfully close to displacing the Smartwool NTS Mid 250 Crew for the Editors' Choice honor. This top exhibits great performance in many categories: warmth, breathability, drying speed, and comfort. We also like the styling for any social engagement, and its technical attributes qualify it for any winter adventure.

Along with the other merino wool options, the material raises durability questions. For a burlier base layer we recommend the Patagonia Capilene 3 Crew, but this top should be considered by those looking for the highest in performance, without concern for strength.

RELATED: Our complete review of long underwear - men's

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Analysis and Hands-on Test Findings

Review by:
Jack Cramer
Review Editor

Last Updated:
March 30, 2015
This is the base layer with the densest woven merino wool we saw. It was the overall favorite of at least one of our testers, but lost out in the final standings due to just a couple details.

Performance Comparison

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Grant Kleeves (left) and Jack Cramer (right) celebrating a mixed climbing first ascent while testing the Icebreaker Oasis and Patagonia Capilene 4 Expedition Weight 1/4 Zip Hoody, respectively (underneath numerous other layers). Now, how to get down with only one headlamp?


The 200 g/m merino wool on the Icebreaker Oasis provides a moderate level of insulation compared with the others tested, and results in a top weighing 8.2 ounces in total. We think this medium warmth is ideal for giving a shirt the maximum number of uses. It is warm enough to keep you toasty in a blizzard as the first layer in a multi-layer system, yet light enough on its own to let heat escape during vigorous exercise at moderate temps.


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Gear testing and rock climbing in Ouray, CO. Although we wore this top expecting a cold day, full sunshine surprised us. With the great breathability of the Icebreaker Oasis it wasn't a problem.
Like the rest of the merino wool shirts in this review, this long underwear performs above average in breathability. Give credit for this advantage to the superior warmth-to-weight ratio of this fabric over synthetics. This allows a top of equal warmth to be made of thinner material and predictably breathe better. This base layer scored a tiny bit higher than the Smartwool NTS Mid 250 Crew, but not as well as the Patagonia Merino 2 Lightweight Henley.

Drying Speed

In the air dry test, this shirt finished in a cluster of three tops just behind the fastest drying, Merino 2 Henley. The actual time was 20% slower, but that leaves it far ahead of the worst finishers. When you combine this strong showing with merino wool's resistance to absorb water, or even feel wet, you have an even better performance.

Layering Ability

From the breathability and drying speed metrics we know that this shirt works great as a next-to-skin layer, but its relaxed fit allows it to also substitute as an insulating layer over a thin shirt. This capability gives you options for truly cold weather and even more uses for an expensive purchase.


Merino wool clothing needs to be handled carefully, and the Oasis is no exception. This top is susceptible abrasion, and caution should be used when machine drying to avoid shrinkage. The fabric, however, will not absorb odors like a synthetic so it should not have to be washed as frequently; extending longevity.

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A comparison of the sleeve stitching on the Smartwool NTS Mid 250 Crew (tan), Patagonia Merino 2 Lightweight Henley (striped blue), and Icebreaker Oasis (solid blue). All were equally durable, but the Smartwool was the most comfortable.

The denser weave of the Icebreaker fabric relative to the Smartwool led one tester to speculate that it would be more durable. We saw the logic in this theory but were unable to substantiate it in our tests.

Comfort and Fit

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The Icebreaker Oasis will rise up a little with arms overhead.
We found this long underwear to be exceptionally comfortable and fit well. It feels light on the skin and the merino wool wasn't scratchy. With that said, this is the one category in which the Smartwool performed subtly, but definitively better, and the ultimate reason why that top took home Editors' Choice instead of this one. When examined closely, there are two notable differences. The Smartwool fabric is stretchier and that helps it conform to movements better. Additionally, the curved seams on the shoulder and back of the Smartwool were more comfortable with a pack on than the right angle construction of the Oasis.

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Subtle difference in the shoulder stitching of the Smartwool NTS Mid 250 Crew (tan) and the Icebreaker Oasis (blue). The more comfortable curved stitching on the Smartwool was the deciding difference between these two great layers.

Best Applications

The uses for this base layer are nearly unlimited. From low to high intensity, frigid to mild temperatures, it performs well. The attractive styling increases its potential from backcountry adventures to a fashionable night on the town. The 50+ UPF rating for the fabric makes this a good option for particularly high sunlight scenarios.


At $90, the Oasis is 5 bucks less than the closely comparable Smartwool. Neither shirt is cheap, but with their quality construction and attentive designs, you receive a lot of value. When handled with care, both tops should last for many years.


Across all of the performance metrics this base layer never came in first, but its strong finish in each category resulted in a well-balanced and functional top. There could only be one Editors' Choice, and after much frustration, we went with the Smartwool, but some of our testers still disagree. Thorough shoppers should take a close look at this shirt because personal preferences in weight, warmth, or styling could easily make this your particular favorite.

Other Versions and Accessories

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Oasis Leggings
  • Cost - $90
  • 200 gram merino wool
  • Comfortable, flat seams

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Oasis Long Sleeve Half Zip
  • Cost - $100
  • 200 gram merino wool
  • Half zipper

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Oasis Short Sleeve Crew
  • Cost - $75
  • 200 gram merino wool

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Oasis Long Sleeve Half Zip Hood
  • Cost - $110
  • 200 gram merino wool
  • half neck zip with hood
Jack Cramer

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OutdoorGearLab Member Reviews

Most recent review: March 30, 2015
Summary of All Ratings

OutdoorGearLab Editors' Rating:   
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Average Customer Rating:     (0.0)
Rating Distribution
1 Total Ratings
5 star: 100%  (1)
4 star: 0%  (0)
3 star: 0%  (0)
2 star: 0%  (0)
1 star: 0%  (0)

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