loaded 489 results

Outdoor Underwear

(489 products)

Products (489)

Sort: Best Match

SmartwoolClassic All-Season Merino T-Shirt - Men's
$80.00
53 reviews with an average rating of 4.2 out of 5 stars
Top Rated
SmartwoolClassic All-Season Merino Long-Sleeve Base Layer Top - Men's
$90.00
56 reviews with an average rating of 4.6 out of 5 stars
REI Co-opMidweight Long-Sleeve Base Layer Top - Women's
$54.95
239 reviews with an average rating of 4.3 out of 5 stars
SmartwoolClassic Thermal Merino Base Layer Bottoms - Women's
$56.83 - $115.00
735 reviews with an average rating of 4.5 out of 5 stars
REI Co-opLightweight Long-Sleeve Crew Base Layer Top - Women's
$39.95
4 reviews with an average rating of 4.8 out of 5 stars
REI Co-opMidweight Base Layer Tights - Women's
$54.95
89 reviews with an average rating of 4.1 out of 5 stars
REI Co-opMerino 185 Long-Sleeve Base Layer Top - Women's
$79.95
193 reviews with an average rating of 4.5 out of 5 stars
REI Co-opLightweight Long-Sleeve Crew Base Layer Top - Men's
$39.95
1 reviews with an average rating of 5.0 out of 5 stars
Top Rated
SmartwoolClassic Thermal Merino Base Layer Bottoms - Men's
$115.00
615 reviews with an average rating of 4.7 out of 5 stars
BrooksConvertible 2.0 Sports Bra
$60.00
86 reviews with an average rating of 3.6 out of 5 stars
REI Co-opMerino 185 Base Layer Bottoms - Men's
$39.83 - $79.95
124 reviews with an average rating of 4.4 out of 5 stars
Top Rated
REI Co-opMidweight Long-Sleeve Base Layer Top - Men's
$54.95
150 reviews with an average rating of 4.5 out of 5 stars
REI Co-opMerino 185 Long-Sleeve Base Layer Top - Men's
$79.95
172 reviews with an average rating of 4.5 out of 5 stars
REI Co-opMidweight Base Layer Bottoms - Men's
$54.95
77 reviews with an average rating of 4.4 out of 5 stars
SmartwoolClassic All-Season Merino Long-Sleeve Base Layer Top - Women's
$62.93 - $90.00
105 reviews with an average rating of 4.4 out of 5 stars
JanjiGroundwork Long Bra
$68.00
9 reviews with an average rating of 4.2 out of 5 stars
REI Co-opLightweight Crew Base Layer Top - Women's
$29.95
2 reviews with an average rating of 5.0 out of 5 stars
Top Rated
VuoriAllTheFeels Bra
$58.00
5 reviews with an average rating of 5.0 out of 5 stars
REI Co-opMerino 185 Base Layer Top - Women's
$69.95
41 reviews with an average rating of 4.4 out of 5 stars
NikeIndy High-Support Bra
$50.00
32 reviews with an average rating of 3.8 out of 5 stars
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
REI Co-opMerino 185 Base Layer Bottoms - Women's
$79.95
103 reviews with an average rating of 4.3 out of 5 stars
SmartwoolClassic All-Season Merino Base Layer Bottoms - Men's
$90.00
18 reviews with an average rating of 4.1 out of 5 stars
Arc'teryxRho LT Base Layer Bottoms - Men's
$70.83 - $100.00
46 reviews with an average rating of 4.4 out of 5 stars
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
PatagoniaLive Simply Bra
$55.00
0 reviews
NikeSwoosh Medium Support Bra
$40.00
106 reviews with an average rating of 4.2 out of 5 stars
OiselleHi Twenty Bra
$58.00
1 reviews with an average rating of 5.0 out of 5 stars
SmartwoolClassic All-Season Merino Quarter-Zip Base Layer Top - Men's
$95.00
1 reviews with an average rating of 5.0 out of 5 stars
BrooksRacerback 2.0 Sports Bra
$21.83 - $75.00
287 reviews with an average rating of 3.4 out of 5 stars

1–30 of 489 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