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Outdoor Underwear

(511 products)

Products (511)

Sort: Best Match

Arms of Andes300 Lightweight Alpaca Wool Pullover Base Layer Hoodie - Women's
$140.00
1 reviews with an average rating of 5.0 out of 5 stars
OiselleFlyout Bra
$68.00
2 reviews with an average rating of 4.5 out of 5 stars
Top Rated
REI Co-opActive Thong Underwear - Women's
$14.95
16 reviews with an average rating of 4.5 out of 5 stars
SmartwoolIntraknit Thermal Merino Crew Base Layer Top - Women's
$64.83 - $130.00
188 reviews with an average rating of 4.3 out of 5 stars
Arms of Andes160 Ultralight Alpaca Wool Long-Sleeve Base Layer Shirt - Women's
$85.00 - $100.00
11 reviews with an average rating of 3.8 out of 5 stars
SmartwoolClassic Thermal Merino Colorblock Crew Base Layer Top - Men's
$59.83 - $120.00
1 reviews with an average rating of 5.0 out of 5 stars
Top Rated
Arc'teryxRho LT Crew Neck Base Layer Top - Men's
$70.83 - $100.00
27 reviews with an average rating of 4.8 out of 5 stars
Top Rated
Icebreaker200 Oasis Long-Sleeve Half-Zip Base Layer Top - Women's
$115.00
16 reviews with an average rating of 4.9 out of 5 stars
Helly HansenLifa Merino Midweight Base Layer Pants - Men's
$100.00
1 reviews with an average rating of 5.0 out of 5 stars
SmartwoolIntraknit Strappy Bra
$75.00
1 reviews with an average rating of 3.0 out of 5 stars
REI Co-opHeavyweight Merino Long-Sleeve Base Layer Crew Top - Men's
$49.83 - $99.95
21 reviews with an average rating of 4.3 out of 5 stars
REI Co-opMerino Thong Underwear - Women's
$24.95
32 reviews with an average rating of 4.2 out of 5 stars
Kari TraaRose High-Waisted Base Layer Pants - Women's
$110.00
24 reviews with an average rating of 4.4 out of 5 stars
PatagoniaCapilene Thermal Weight Long Underwear Bottoms - Women's
$99.00
14 reviews with an average rating of 3.6 out of 5 stars
Top Rated
REI Co-opMidweight Crew Base Layer Top - Toddlers'
$24.95
14 reviews with an average rating of 4.7 out of 5 stars
Arms of Andes160 Ultralight Alpaca Wool Crew Neck Base Layer T-Shirt - Women's
$75.00
2 reviews with an average rating of 5.0 out of 5 stars
Top Rated
Arms of Andes300 Lightweight Alpaca Wool Base Layer Leggings - Women's
$105.00
8 reviews with an average rating of 5.0 out of 5 stars
Ortovox120 Comp Light Short Base Layer Pants - Men's
$70.00
3 reviews with an average rating of 5.0 out of 5 stars
Top Rated
IcebreakerMerino 150 Tech Lite III Relaxed T-Shirt - Women's
$80.00
71 reviews with an average rating of 4.6 out of 5 stars
SmartwoolIntraknit Strappy Bra
$65.00
2 reviews with an average rating of 5.0 out of 5 stars
Oya Femtech ApparelRemovable Inserts - Women's - Package of 4
$20.00
17 reviews with an average rating of 3.8 out of 5 stars
NRSH2Core Lightweight Union Suit - Men's
$109.95
2 reviews with an average rating of 3.0 out of 5 stars
REI Co-opMerino 185 Base Layer Top - Men's
$69.95
51 reviews with an average rating of 4.2 out of 5 stars
Oya Femtech ApparelHigh-Impact Front Zip Sports Bra
$55.00
7 reviews with an average rating of 4.1 out of 5 stars
SmartwoolIntraknit Bikini Underwear - Women's
$34.00
5 reviews with an average rating of 1.8 out of 5 stars
SmartwoolIntraknit Racerback Bra
$75.00
0 reviews
REI Co-opMerino Boxers - Men's
$39.95
65 reviews with an average rating of 4.3 out of 5 stars
SaxxDropTemp Cooling Mesh Boxer Briefs - Men's
$38.00
38 reviews with an average rating of 3.9 out of 5 stars
Top Rated
The North FaceSummit Series Pro 120 Crew Base Layer Top - Women's
$100.00
12 reviews with an average rating of 5.0 out of 5 stars
REI Co-opActive Hipster Underwear - Women's
$18.95
35 reviews with an average rating of 3.8 out of 5 stars

151–180 of 511 products

Sort: Best Match

Related Expert Advice articles

What material is best?

Wool is moisture-wicking and odor-resistant, while synthetic fabrics are more durable and less expensive.

Match the temp to the trek

Lightweight layers are best for moderate to cool temperatures. Midweight layers are best for cold temperatures. Heavyweight layers are best for below-freezing temperatures.

Find your fit

To be able to wick sweat efficiently, your next-to-skin layer needs to actually be next to your skin. A comfortably snug fit everywhere is your goal.

Read full article: How to Choose Base Layers