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  • Soft, nonirritating merino wool offers lightweight warmth next to skin and resists odors naturally
  • Lightweight merino wool wicks away moisture, dries quickly and breathes well to regulate temperature for outstanding warmth in cool weather
  • Fabric offers protection from UV light with a rating of UPF 50+
  • Flatlock seams reduce chafing, offset shoulder seams will not rub under backpack straps and side seams wrap toward the back to prevent hipbelt chafing
  • Machine washable; line dry or dry flat in shade
  • The women's Icebreaker Oasis crew long underwear top has a slim fit


View all Icebreaker Women's Long Underwear Tops

REI membership


Best Use Multisport
Shirt Style Crew
Fabric Merino wool
Sun-Protective Fabric Yes
UPF Rating 50
Moisture Wicking Yes
Quick Drying Yes
Underwear Weight Lightweight
Sleeve Length Long Sleeve
Gender Women's

Size chart

Sizing notes

Measurements are stated in inches unless otherwise indicated. CHOOSING THE RIGHT SIZE: If your body measurements are midway between two sizes, select the smaller size for a tighter fit or the larger size for a looser fit. If your body measurements result in different sizes, we recommend using your chest measurement for tops and your hip measurement for pants.

Rated 2 out of 5 by from Logo disappointment I cannot say how much I love Icebreaker - except for the visible logos which ruin the otherwise perfect, simple clothing. I wanted to wear this shirt to work but can't since the logo is embroidered prominently on the sleeve! Icebreaker, you could really expand your fan base if you made your clothes more versatile. They don't need to scream with branding, the quality speaks for itself! This one is getting returned. I guess I'll have to stick to the lovely un-logo'd Siren line for now.
Date published: 2014-01-23
Rated 5 out of 5 by from Comfortable, warm, versatile I bought this shirt last winter before competing in a winter triathlon (skate, ski, run) to wear as a base layer in the -14 degree temps during the event. It worked well as a base layer (beneath two other layers) and it was so soft and comfortable to wear! Great drape. I started wearing it a lot, not just for sports but as a general underlayer. I came back this fall and bought it again in a different color. It's perfect for running in 30-45 degree temps, layered under a light long sleeved sports shirt. I wish it had the label on the inside only and came in more colors.
Date published: 2015-11-13
Rated 5 out of 5 by from great base layer Ordered the first one in raspberry, and loved it. Am 5ft 4in and 125lbs, broad shouldered, and selected the small. If you are really busty and carry weight in your tummy, you might want to go up. Obviously being a base layer type piece of clothing, it skims the body close. I wear a lot of vests, and this goes under them nicely without a lot of bulk. The neckline allows me to add a scarf if the weather is chillier. Upon receiving I ordered two more, as these will be my go to layers for the midwest winter.
Date published: 2015-10-07
Rated 4 out of 5 by from Great baselayer I've replaced all my synthetic base layers with Icebreaker and it was a great decision. I've worn this top multiple times on snowboarding trips and it never stinks like my old base layers did. While I still recommend, I'd really like to see Icebreaker design a version of this top with thumbholes and add 2 inches in length because it doesn't stay tucked into my snowboard pants. Otherwise, it's great. I have very sensitive skin and typically hate wearing wool, but merino wool from Icebreaker is very soft and comfy.
Date published: 2015-02-01
Rated 4 out of 5 by from versatile tee I have this one in both black (XS) and mandarin (S). I am 5'3 and 108 lbs. XS is a perfect fit for wearing under another piece. S is still slim due to the tailored waist but more relaxed on arms and chest so I can wear it as a Tee. The only downside is that lighter color one is a bit see-through, so I wear it with a vest, tank, or a jacket. The size S one has longer sleeves too, so I have to do something about it all the time. XS has perfect sleeve length for me.
Date published: 2013-02-16
Rated 5 out of 5 by from Can't beat Icebreaker I bought this in black, size small. (I'm 5'2" and 106 lbs). Fits perfect. So soft and warm! Doesn't seem as tight fitting as some base layers, and I didn't want it to. I like that I can push the sleeves up if I want. The bottom of the shirt is long enough to tuck in or otherwise not ride up. Good to have that extra fabric on the bottom. Throw a scarf on my neck, and it looks good as an outer layer. The neckline is higher than I would have chosen, but that does help with warmth.
Date published: 2015-01-13
Rated 5 out of 5 by from Own several of these - feels great, versatile I've been a fan of Icebreaker for 10 years since discovering the brand, when my hiking guide in New Zealand, said, "here smell this, I've been wearing it for several days now and it doesn't stink." It's not just that though. It's the only wool I can wear next to my skin without itching. This lightweight top is silky smooth. I have it in several colors, including two in light gray because it's such a versatile neutral. It works well stand-alone or as a base layer. Sizing with Icebreaker is up to individual taste. I'm 5-4-1/2 inches, 116 lbs, small busted but moderately broad shoulders. I don't like my tops tight, so I generally buy a medium in the regular Icebreaker fit and t-shirt styles and a large in the GT and Body fit styles. The only drawback to this approach is the sleeves are a little long for me in the large. If you like your tops more fitted, size accordingly. Icebreaker tops are all cut quite long in the torso.
Date published: 2013-12-07
Rated 5 out of 5 by from Love this shirt! Super comfortable, and the panels under the arms make it move well. (Though it's not GT, it's definitely suitable for light active use.) Only downside is that the beautiful green is a little bit see through-- I have to wear a plain coloured rather than patterned bra underneath.
Date published: 2013-02-09
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