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Outdoor Underwear

(517 products)

Products (517)

Sort: Best Match

SmartwoolIntraknit Strappy Bra
$75.00
1 reviews with an average rating of 3.0 out of 5 stars
REI Co-opHeavyweight Merino Base Layer Half-Zip Top - Men's
$49.83 - $104.95
15 reviews with an average rating of 3.9 out of 5 stars
REI Co-opMerino 185 Long-Sleeve Half-Zip Base Layer Top - Women's Plus Sizes
$62.93 - $89.95
18 reviews with an average rating of 4.3 out of 5 stars
Outdoor ResearchVantage Printed Crop Top
$38.73
Save 29%
compared to $55.00
1 reviews with an average rating of 4.0 out of 5 stars
REI OUTLET
Top Rated
Arc'teryxRho Heavyweight Base Layer Bottoms - Men's
$59.83
Save 50%
compared to $120.00
62 reviews with an average rating of 4.7 out of 5 stars
IcebreakerMerino 260 Vertex Long-Sleeve Crewe Natural Shades Base Layer Top - Women's
$104.73
Save 25%
compared to $140.00
2 reviews with an average rating of 5.0 out of 5 stars
REI OUTLET
SmartwoolClassic All-Season Merino Quarter-Zip Base Layer Top - Women's
$95.00
1 reviews with an average rating of 5.0 out of 5 stars
Top Rated
Arc'teryxRho Merino Wool Crew Neck Base Layer Top - Men's
$59.83 - $120.00
27 reviews with an average rating of 4.8 out of 5 stars
Outdoor ResearchVantage Bra
$39.73
Save 27%
compared to $55.00
2 reviews with an average rating of 4.5 out of 5 stars
REI OUTLET
PatagoniaCapilene Thermal Weight Zip-Neck Long Underwear Top - Women's
$109.00
14 reviews with an average rating of 4.1 out of 5 stars
Free CountryForce Grid Fleece Base Layer Top - Women's
$34.73
Save 36%
compared to $55.00
1 reviews with an average rating of 5.0 out of 5 stars
REI OUTLET
Top Rated
SmartwoolClassic Thermal Merino Crew Base Layer Top - Men's
$85.73
Save 25%
compared to $115.00
276 reviews with an average rating of 4.7 out of 5 stars
REI OUTLET
REI Co-opLightweight Half-Zip Base Layer Top - Women's
$44.95
1 reviews with an average rating of 5.0 out of 5 stars
CraftCORE Dry Active Comfort Base Layer Top - Women's
$39.73
Save 38%
compared to $64.95
3 reviews with an average rating of 3.7 out of 5 stars
REI OUTLET
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
Top Rated
SmartwoolClassic Thermal Merino Quarter-Zip Base Layer Top - Men's
$120.00
18 reviews with an average rating of 4.6 out of 5 stars
Top Rated
PatagoniaCapilene Midweight Crew Base Layer Top - Women's
$89.00
45 reviews with an average rating of 4.6 out of 5 stars
Top Rated
Icebreaker260 Tech Long-Sleeve Crewe Base Layer Top - Women's
$125.00
36 reviews with an average rating of 4.7 out of 5 stars
StanceSanta Rips Boxer Briefs - Men's
$22.73
Save 35%
compared to $35.00
0 reviews
REI OUTLET
SmartwoolIntraknit Strappy Bra
$65.00
3 reviews with an average rating of 3.7 out of 5 stars
StanceInvestor Boxer Briefs - Men's
$22.73
Save 24%
compared to $30.00
3 reviews with an average rating of 4.7 out of 5 stars
REI OUTLET
SaxxDropTemp Cooling Mesh Boxer Briefs - Men's
$38.00
41 reviews with an average rating of 3.8 out of 5 stars
BrooksRacerback 2.0 Sports Bra
$75.00
291 reviews with an average rating of 3.5 out of 5 stars
Top Rated
IcebreakerMerino 260 Tech Long-Sleeve Half-Zip Base Layer Top - Women's
$135.00
25 reviews with an average rating of 4.6 out of 5 stars
BurtonMidweight Base Layer Pants - Women's
$19.83
Save 69%
compared to $64.95
0 reviews
REI Co-opLightweight Half-Zip Base Layer Top - Men's
$44.95
4 reviews with an average rating of 4.8 out of 5 stars
GlyderEase Bra
$39.73
Save 26%
compared to $54.00
0 reviews
REI OUTLET
Kari TraaRose Half-Zip Base Layer Top - Women's
$120.00 - $130.00
30 reviews with an average rating of 4.5 out of 5 stars
SmartwoolIntraknit Racerback Bra
$65.00
3 reviews with an average rating of 3.0 out of 5 stars
Top Rated
REI Co-opLightweight Base Layer Tights - Women's
$39.95
7 reviews with an average rating of 4.6 out of 5 stars

91–120 of 517 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