Base Layers and Underwear

The best base layers and underwear, reviewed and curated by the Trailspace community. The latest review was added on May 5, 2020. Stores' prices and availability are updated daily.

Recent Base Layer Reviews

rated 4 of 5 stars
Smartwool Men's Intraknit Merino 250 Thermal 1/4 Zip

The Smartwool Intraknit Merino 250 Thermal Quarter Zip brings 100% Merino wool in a comfortable and warm weave. This shirt works as a base, mid, outer and only layer depending on conditions, activity and the wearer's temperament. Versatile enough to handle a wide variety of cold weather activities. Smartwool takes a technical leap forward with their newly designed Intraknit Merino 250 Thermal 1/4 Zip and I've had the pleasure of extensively testing it over the last four months. Along with their… Full review

rated 4.5 of 5 stars
Outdoor Research Men's Enigma Bottoms

The Outdoor Research Enigma Bottom is a base layer whose forte is wicking moisture and keeping you dry when you’re active; though the fabric has some wool content, it’s mostly synthetic (12% merino, 88% polyester). The fabric is relatively thin and very stretchy and slightly prone to pilling in high-friction areas. It’s an outstanding option for high-output cool and cold weather activities (four-season if you live in a cooler place), except you’ll want to wear them under a shell or fleece… Full review

rated 4.5 of 5 stars
Outdoor Research Men's Enigma Half Zip

The Enigma Half Zip is a base layer that places wicking moisture and drying quickly at a premium. That's a little unusual for a shirt that's partially made of merino wool, but in this case, the blend is 88 percent synthetic, 12 percent wool. Choose this shirt for high-sweat, high-output activities; consider a thicker/heavier base layer for bitter cold. The relatively light fabric and great moisture management makes this an attractive layer year-round until it's so warm that you're better off in… Full review

rated 4.5 of 5 stars
Outdoor Research Enigma Boxer Briefs

Close-fitting as a boxer brief intended for active use should be, the Enigma Boxer Briefs feel good, wick extremely well, and appear to be durable. This is mostly-nylon with 12 percent merino wool. It's quite stretchy and performs more like nylon than wool. Though the fabric is thin, it seems like it should last. Mixing in wool helps blunt the odor factor, too. HOW THEY FIT The Enigma Boxer Brief is a relatively short (6 1/2 inch inseam) and stretchy boxer made from the same material as Outdoor… Full review

rated 4.5 of 5 stars
Black Diamond Men's Solution 150 Merino Base 3/4

Black Diamond's Solution 150 Merino Base 3/4 is a lightweight, polyester-reinforced merino wool base layer. Cool enough to wear under light shell clothing for high intensity activity at around-freezing temperatures without overheating, but easily layered over for use in colder conditions or at lower intensity. Stretch fabric gives a comfortable fit even on a slim frame and dries a little faster than 100 percent merino. 3/4 length works with high plastic cuff ski boots. (Preliminary review based… Full review

rated 4.5 of 5 stars
Black Diamond Men's Solution 150 Merino Base Crew

Black Diamond's Solution 150 Merino Base Crew is a lightweight, polyester-reinforced merino wool base layer. Cool enough to wear under light shell clothing for high intensity activity at around-freezing temperatures without overheating, but easily layered over for use in colder conditions or at lower intensity. Stretch fabric gives a comfortable fit even on a slim frame and dries a little faster than 100 percent merino. (Preliminary review based on the first month of use) Black Diamond’s Solution… Full review

rated 4.5 of 5 stars
Kari Traa Rose Long Sleeve

The Kari Traa Rose Longsleeve is a 100 percent merino base layer that is comfortable, warm, and durable. It's thin enough to layer without restricting movement, and incorporates a range of colors and sizes to appeal to a variety of adventurous ladies! Just be prepared to size up as this base layer runs SMALL! Testing Conditions: I tested the Kari Traa Rose Longsleeve from December 2018 to December 2019 as a member of the Trailspace Review Corps. Testing conditions ranged from -25 to 20 degrees… Full review

rated 4.5 of 5 stars
Kari Traa Rose Pant

The Kari Traa Rose Pant is a 100 percent merino base layer that is comfortable, warm, and durable. It's thin enough to layer without restricting movement, and incorporates a range of colors and sizes to appeal to a variety of adventurous ladies! Just be prepared to size up as this base layer runs SMALL! Testing Conditions: I tested the Kari Traa Rose Pant from December 2018 to December 2019 as a member of the Trailspace Review Corps. Testing conditions ranged from -25 to 20 degrees Fahrenheit in… Full review

rated 4.5 of 5 stars
Smartwool Merino Sport 150 Brief

Super comfortable undies, which will help you stay sweet smelling for days, with no chafing. Yeah, I'm reviewing underwear. Being a big Merino fan, I decided it was time to take the final step towards full commitment, by going right down to the basics. I decided to give these a try.   Fit: The overall fit is good. I'd read a couple of reviews criticizing the extra wide waistband, but in my opinion, it makes them much more stable and keeps them in place better than other briefs I've used. I like… Full review

user rating: 4.5 of 5 (9)
ExOfficio Give-N-Go Boxer Brief Boxer/Brief/Bikini
$13 - $26
user rating: 5 of 5 (2)
Arc'teryx Rho LT Zip Neck Top
$69 - $125
user rating: 5 of 5 (2)
Patagonia R1 Pants Bottom / Fleece
$119
user rating: 5 of 5 (1)
Fjallraven Bergtagen Longjohns Bottom
$105 - $140
user rating: 5 of 5 (1)
Smartwool Midweight Crew Top
$36 - $100
user rating: 5 of 5 (1)
Icebreaker Siren Bra Sports Bra
$38 - $50
user rating: 5 of 5 (1)
ExOfficio Give-N-Go Lacy Bikini Boxer/Brief/Bikini
$11
user rating: 5 of 5 (1)
Patagonia Capilene Thermal Weight Bottoms Bottom
$53 - $89
user rating: 5 of 5 (1)
Smartwool NTS Mid 250 Bottom Bottom
$50
user rating: 5 of 5 (1)
Marmot Lightweight Bottom Bottom
$29 - $118
user rating: 5 of 5 (1)
Fjallraven Bergtagen Woolmesh Sweater Top
$120 - $160
user rating: 5 of 5 (1)
Marmot Midweight Crew LS Top
$60
user rating: 5 of 5 (1)
Patagonia Capilene 3 Midweight Bottoms Bottom
$18 - $59
user rating: 4.5 of 5 (1)
Outdoor Research Enigma Boxer Briefs Boxer/Brief/Bikini
$20 - $34
user rating: 4.5 of 5 (1)
Helly Hansen HH Lifa Merino Pant Bottom
$67
user rating: 4.5 of 5 (1)
Patagonia Capilene Air Bottoms Bottom
$90 - $129
user rating: 4.5 of 5 (1)
Outdoor Research Enigma Bottoms Bottom
$32 - $69
user rating: 4.5 of 5 (1)
Outdoor Research Enigma Half Zip Top
$47 - $79
user rating: 4.5 of 5 (1)
Black Diamond Solution 150 Merino Base 3/4 Bottom
$95
user rating: 4.5 of 5 (1)
Black Diamond Solution 150 Merino Base Crew Top
$119
user rating: 4.5 of 5 (1)
Craft Active Extreme 2.0 CN LS Top Top
$45
user rating: 4.5 of 5 (1)
ExOfficio Give-N-Go Sport Mesh Brief Boxer/Brief/Bikini
$14 - $21
user rating: 4.5 of 5 (1)
Helly Hansen HH Lifa Merino 1/2 Zip Top
$53 - $73
user rating: 4.5 of 5 (1)
Patagonia Capilene Thermal Weight Zip-Neck Top
$65 - $99
user rating: 4.5 of 5 (1)
Kari Traa Rose Long Sleeve Top
$60 - $78
user rating: 4.5 of 5 (1)
Icebreaker Anatomica Brief Boxer/Brief/Bikini
$21 - $40
user rating: 4.5 of 5 (1)
Airblaster Ninja Suit One-Piece Base Layer
$55 - $109
user rating: 4.5 of 5 (1)
Patagonia Capilene Air Hoody Top
$75 - $149
user rating: 4.5 of 5 (1)
Kari Traa Rose Pant Bottom
$50 - $78
user rating: 4.5 of 5 (1)
Smartwool Merino Sport 150 Brief Boxer/Brief/Bikini
$19 - $25
user rating: 4 of 5 (2)
Patagonia Capilene Air Crew Top
$65 - $129
user rating: 4 of 5 (2)
Outdoor Research ActiveIce Sun Sleeves Arm/Leg Sleeve
$29 - $34
user rating: 4 of 5 (1)
SportHill Northwind Unders Boxer/Brief/Bikini
$35
user rating: 4 of 5 (1)
ExOfficio Sol Cool Boxer Brief Boxer/Brief/Bikini
$17 - $28
user rating: 4 of 5 (1)
Terramar Thermolator II Pant Bottom
$15
user rating: 4 of 5 (1)
Smartwool Intraknit Merino 250 Thermal 1/4 Zip Top
$75 - $150
user rating: 3.5 of 5 (2)
ExOfficio Give-N-Go Boxer Boxer/Brief/Bikini
$15 - $26
user rating: 3.5 of 5 (1)
Toad&Co Pacer Slim Long Sleeve Quarter Zip Top
$75
user rating: 3 of 5 (1)
Minus33 Isolation Midweight Merino Zip-Neck Top
$63
user rating: 2.5 of 5 (1)
Garneau Arm Coolers Arm/Leg Sleeve
$30
user rating: 2 of 5 (1)
Terramar Silk Pant Bottom
$26 - $55
NEW!
Smartwool Merino Sport 150 Hidden Pocket Top / Short Sleeve Performance
$49 - $65
Smartwool Intraknit Merino 250 Thermal Bottom Bottom
$98 - $130
NEW!
Appalachian Gear Company All-Paca Crew Long Sleeve Performance Top / Top
$145
available Spring 2020
user rating: 5 of 5 (6)
Patagonia Capilene 2 Lightweight Zip-Neck Top
user rating: 5 of 5 (3)
Icebreaker Bodyfit 150 Long Sleeve Crewe Top
user rating: 5 of 5 (2)
Icebreaker 260 Midweight Tech Top Top
$110 MSRP
user rating: 5 of 5 (2)
Icebreaker Oasis Long Sleeve Crewe Top
user rating: 5 of 5 (2)
Marmot Lightweight Crew LS Top
$45 MSRP
user rating: 5 of 5 (2)
Marmot Midweight Bottom Bottom
$50 MSRP
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