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Smartwool Underwear: Deals

(41 products)

Products (41)

Sort: Best Match

SmartwoolClassic All-Season Merino Long-Sleeve Base Layer Top - Women's
$49.83 - $100.00
99 reviews with an average rating of 4.4 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Plus
SmartwoolIntraknit Thermal Merino Crew Base Layer Top - Men's
$59.83 - $150.00
139 reviews with an average rating of 4.3 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
SmartwoolClassic Thermal Merino Colorblock Crew Base Layer Top - Men's
$96.73
Save 25%
compared to $130.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
2 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI OUTLET
Top Rated
SmartwoolClassic Thermal Merino Base Layer Quarter-Zip - Women's
$89.73
Save 25%
compared to $120.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
83 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
Top Rated
SmartwoolClassic Thermal Merino Quarter-Zip Base Layer Top - Women's
$89.93 - $130.00
83 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Plus
SmartwoolClassic Thermal Merino Crew Base Layer Top - Kids'
$44.73
Save 25% - 31%
compared to $60.00 - $65.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
7 reviews with an average rating of 3.9 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
Top Rated
SmartwoolClassic Thermal Merino Crew Base Layer Top - Men's
$84.73
Save 26%
compared to $115.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
325 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI OUTLET
SmartwoolIntraknit Thermal Merino Crew Base Layer Top - Women's
$49.83 - $150.00
135 reviews with an average rating of 4.1 out of 5 stars
Underwear Weight:
Heavyweight
Size Type:
Regular
SmartwoolActive Crop Bra
$55.93
Save 25%
compared to $75.00
4 reviews with an average rating of 3.8 out of 5 stars
Bra Support:
Low Impact
Support Style:
Compression
Fabric:
Main: 87% nylon/13% elastane (exclusive of decoration)
SmartwoolClassic All-Season Merino Base Layer Bottoms - Women's
$66.73
Save 25%
compared to $90.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
0 reviews
Underwear Weight:
Lightweight
Size Type:
Regular
REI OUTLET
SmartwoolClassic Thermal Merino Crew Base Layer Top - Women's
$84.73
Save 26%
compared to $115.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
1 reviews with an average rating of 4.0 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
SmartwoolClassic All-Season Merino Base Layer Bottoms - Women's
$49.83 - $100.00
26 reviews with an average rating of 4.3 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Plus
Top Rated
SmartwoolClassic Thermal Merino Base Layer Quarter-Zip - Men's
$89.73
Save 25%
compared to $120.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
65 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI OUTLET
Top Rated
SmartwoolClassic Thermal Merino Base Layer Bottoms - Women's Plus Sizes
$49.83 - $125.00
20 reviews with an average rating of 4.5 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Plus
Top Rated
SmartwoolClassic Thermal Merino Crew Base Layer Top - Women's
$81.73 - $84.73
Save 26% - 28%
compared to $115.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
451 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
SmartwoolClassic Thermal Merino Base Layer Quarter-Zip - Kids'
$49.73
Save 28%
compared to $70.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
0 reviews
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
SmartwoolIntraknit Thermal Merino Base Layer Quarter-Zip Top - Men's
$104.73
Save 25%
compared to $140.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
0 reviews
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI OUTLET
SmartwoolClassic Thermal Merino Base Layer Bottoms - Women's
$84.73
Save 26%
compared to $115.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
284 reviews with an average rating of 4.3 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
SmartwoolIntraknit Thermal Merino Colorblock Quarter-Zip Base Layer Top - Women's
$49.83 - $140.00
8 reviews with an average rating of 4.3 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
SmartwoolIntraknit Thermal Merino Base Layer 3/4 Bottoms - Men's
$89.73
Save 25%
compared to $120.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
0 reviews
Underwear Weight:
Lightweight
Size Type:
Regular, Big
REI OUTLET
SmartwoolIntraknit 6" Boxer Briefs - Men's
$36.73
Save 26%
compared to $50.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
7 reviews with an average rating of 3.1 out of 5 stars
Size Type:
Regular
REI OUTLET
SmartwoolClassic Thermal Merino Base Layer Bottoms - Kids'
$48.73
Save 25%
compared to $65.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
1 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
SmartwoolClassic Thermal Merino Half-Zip Base Layer Hoodie - Women's
$108.73
Save 25%
compared to $145.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
1 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
SmartwoolClassic Thermal Merino Base Layer Hoodie - Men's
$108.73
Save 25%
compared to $145.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
4 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI OUTLET
SmartwoolIntraknit Thermal Merino Crew Base Layer Top - Women's
$96.73
Save 25%
compared to $130.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
135 reviews with an average rating of 4.1 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
Top Rated
SmartwoolClassic All-Season Merino Quarter-Zip Base Layer Top - Women's
$69.73
Save 26%
compared to $95.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
9 reviews with an average rating of 4.6 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular
REI OUTLET
Top Rated
SmartwoolClassic All Season Merino Long-Sleeve Base Layer Top - Men's
$66.73
Save 25%
compared to $90.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
19 reviews with an average rating of 4.7 out of 5 stars
Underwear Weight:
Lightweight
Size Type:
Regular, Big
REI OUTLET
SmartwoolIntraknit Merino 3/4 Base Layer Bottoms - Women's
$89.73
Save 25%
compared to $120.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
0 reviews
Underwear Weight:
Midweight
Size Type:
Regular
REI OUTLET
SmartwoolIntraknit Thermal Merino Base Layer Hoodie - Men's
$134.73
Save 25%
compared to $180.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
2 reviews with an average rating of 5.0 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI OUTLET
SmartwoolIntraknit Thermal Merino Base Layer Colorblock Crew - Men's
$96.73
Save 25%
compared to $130.00
Members use code OUT4JUL26 for $20 off $100+ at REI Outlet thru 7/6.
4 reviews with an average rating of 4.3 out of 5 stars
Underwear Weight:
Midweight
Size Type:
Regular, Big
REI OUTLET

1–30 of 41 products

Sort: Best Match

Related Expert Advice articles

Fabrics

Synthetic: moisture-wicking, quick drying, durable, but can hold on to odor
Wool: moisture-wicking, odor-resistant, cooling in warm weather, can be less durable

Styles

Bikini: less rear coverage, thinner waistband, higher-cut leg
Briefs (women's): full-cut briefs offer more coverage in front and back; hipsters offer medium front coverage and back with higher rise
Briefs (men's): close fit and good support, but less thigh coverage
Boxer brief or boy shorts: snug fit, good coverage, longer cut extends down to the upper thigh
Boxers: looser fit, added coverage can prevent chafing but prone to bunching
Thongs: lightweight and quick-drying but provide the least coverage
Sports bras: compression and support during high-output activities like hiking and running

Read full article: How to Choose Hiking Underwear

Which material is best?

Wool: highly moisture-wicking and odor-resistant
Synthetic: durable and less expensive
Silk: soft and lightweight for casual activities

Match the temp to the trek

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

Find your fit

Must be close to skin to efficiently wick sweat; should fit comfortably snug
Base layer is for moisture control; your mid layer is for warmth

Read full article: How to Choose Base Layers

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