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Merino Wool Base Layers

(168 products)
Products (168)
Sort: Best Match
    SmartwoolClassic All-Season Merino Long-Sleeve Base Layer Top - Women's
    $49.83 - $74.99
    Save 25% - 50%
    compared to  $100.00
    100 reviews with an average rating of 4.4 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Plus
    Top Rated
    SmartwoolClassic All-Season Merino Long-Sleeve Base Layer Top - Men's
    $39.83 - $74.99
    Save 25% - 60%
    compared to  $100.00
    106 reviews with an average rating of 4.6 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    Top Rated
    REI Co-opMerino 185 Long-Sleeve Half-Zip Base Layer Top - Men's
    $67.39
    Save 25%
    compared to  $89.95
    137 reviews with an average rating of 4.5 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
    Top Rated
    SmartwoolClassic Thermal Merino Quarter-Zip Base Layer Top - Women's
    $49.83 - $97.49
    Save 25% - 61%
    compared to  $130.00
    73 reviews with an average rating of 4.7 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Plus, Regular
  • Sale Ends May 25
    Top Rated
    SmartwoolClassic Thermal Merino Base Layer Bottoms - Men's
    $93.69
    Save 25%
    compared to  $125.00
    647 reviews with an average rating of 4.7 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular, Big
  • Text reads: ‘Anniversary Sale 2026. 25% off’ over a collage of Smartwool long-sleeve shirts and colorful socks.

    Save 25% on all Smartwool clothing

    Top Rated
    SmartwoolClassic Thermal Merino Quarter-Zip Base Layer Top - Men's
    $49.83 - $97.49
    Save 25% - 61%
    compared to  $130.00
    62 reviews with an average rating of 4.7 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular, Big
    Top Rated
    SmartwoolClassic Thermal Merino Crew Base Layer Top - Men's
    $49.83 - $93.69
    Save 25% - 60%
    compared to  $125.00
    1539 reviews with an average rating of 4.7 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular, Big
    SmartwoolClassic All-Season Merino Base Layer Bottoms - Women's
    $49.83 - $74.99
    Save 25% - 50%
    compared to  $100.00
    25 reviews with an average rating of 4.2 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Plus
    Top Rated
    SmartwoolClassic Thermal Merino Crew Base Layer Top - Women's
    $49.83 - $93.69
    Save 25% - 60%
    compared to  $125.00
    1222 reviews with an average rating of 4.7 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular, Plus
    SmartwoolIntraknit Thermal Merino Crew Base Layer Top - Women's
    $49.83 - $112.49
    Save 25% - 66%
    compared to  $150.00
    199 reviews with an average rating of 4.2 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular
  • Sale Ends May 25
    SmartwoolClassic All-Season Merino T-Shirt - Women's
    $59.99 - $71.19
    Save 25% - 36%
    compared to  $95.00
    110 reviews with an average rating of 4.3 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Plus
  • Sale Ends May 25
    SmartwoolClassic Thermal Merino Base Layer Bottoms - Women's
    $63.49
    Save 44%
    compared to  $115.00
    280 reviews with an average rating of 4.3 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular
    REI OUTLET
  • Sale Ends May 25
    Icebreaker125 Cool-Lite Merino Blend Sphere III Scoop T-Shirt - Women's
    $67.49
    Save 25%
    compared to  $90.00
    28 reviews with an average rating of 4.4 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
    SmartwoolIntraknit Thermal Merino Colorblock Crew Base Layer Top - Men's
    $49.83 - $97.49
    Save 25% - 61%
    compared to  $130.00
    12 reviews with an average rating of 4.2 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    REI Co-opMerino 185 Long-Sleeve Base Layer Top - Women's
    $59.89
    Save 25%
    compared to  $79.95
    246 reviews with an average rating of 4.4 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
  • Sale Ends May 25
    REI Co-opMerino 185 Base Layer Bottoms - Women's
    $59.89
    Save 25%
    compared to  $79.95
    122 reviews with an average rating of 4.2 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
    Top Rated
    SmartwoolClassic All-Season Merino Quarter-Zip Base Layer Top - Women's
    $69.73
    Save 26%
    compared to  $95.00
    6 reviews with an average rating of 4.5 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
    REI OUTLET
  • Sale Ends May 25
    REI Co-opMerino 185 Base Layer Top - Men's
    $52.39
    Save 25%
    compared to  $69.95
    60 reviews with an average rating of 4.3 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
  • Sale Ends May 25
    REI Co-opMerino 185 Base Layer Bottoms - Men's
    $59.89
    Save 25%
    compared to  $79.95
    169 reviews with an average rating of 4.2 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
  • Sale Ends May 25
    Top Rated
    IcebreakerMerino 200 Oasis Long-Sleeve Crewe Thermal Top - Women's
    $89.99
    Save 25%
    compared to  $120.00
    181 reviews with an average rating of 4.7 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular, Plus
  • Sale Ends May 25
    Top Rated
    REI Co-opMerino 185 Long-Sleeve Base Layer Top - Men's
    $59.89
    Save 25%
    compared to  $79.95
    228 reviews with an average rating of 4.6 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
    REI Co-opHeavyweight Merino Base Layer Bottoms - Women's
    $29.83 - $99.95
    34 reviews with an average rating of 4.4 out of 5 stars
    Underwear Weight:
    Heavyweight
    Size Type:
    Regular, Plus
  • Sale Ends May 25
    REI Co-opMerino 185 Base Layer Top - Women's
    $52.39
    Save 25%
    compared to  $69.95
    67 reviews with an average rating of 4.3 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular
  • Sale Ends May 25
    SmartwoolClassic Thermal Merino Base Layer Bottoms - Women's
    $93.69
    Save 25%
    compared to  $125.00
    769 reviews with an average rating of 4.4 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular
  • Sale Ends May 25
    SmartwoolClassic All-Season Merino Base Layer Bottoms - Men's
    $74.99
    Save 25%
    compared to  $100.00
    30 reviews with an average rating of 4.3 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Big
    Top Rated
    REI Co-opHeavyweight Merino Base Layer Half-Zip Top - Women's
    $29.83 - $104.95
    35 reviews with an average rating of 4.7 out of 5 stars
    Underwear Weight:
    Heavyweight
    Size Type:
    Regular, Plus
  • Limited time only! The R E I Co-op Mastercard.

    Get $130 in value

    When approved for the REI Co-op Mastercard by May 25, you’ll get $30 in card rewards. Plus, you can earn a $100 REI gift card after your first non-REI purchase within 60 days from account opening. Terms apply.

    SmartwoolIntraknit Thermal Merino Colorblock Quarter-Zip Base Layer Top - Women's
    $49.83 - $104.99
    Save 25% - 64%
    compared to  $140.00
    8 reviews with an average rating of 4.3 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular
    Top Rated
    REI Co-opHeavyweight Merino Long-Sleeve Base Layer Crew Top - Men's
    $99.95
    50 reviews with an average rating of 4.5 out of 5 stars
    Underwear Weight:
    Heavyweight
    Size Type:
    Regular, Big
    Top Rated
    SmartwoolClassic Thermal Merino Crew Base Layer Top - Women's
    $81.73 - $84.73
    Save 26% - 28%
    compared to  $115.00
    440 reviews with an average rating of 4.7 out of 5 stars
    Underwear Weight:
    Midweight
    Size Type:
    Regular
    REI OUTLET
  • Sale Ends May 25
    Top Rated
    Icebreaker200 Oasis Long-Sleeve Half-Zip Base Layer Top - Women's
    $86.19 - $97.49
    Save 25%
    compared to  $115.00 - $130.00
    42 reviews with an average rating of 4.7 out of 5 stars
    Underwear Weight:
    Lightweight
    Size Type:
    Regular, Plus
Sort: Best Match

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