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Base Layers and Underwear

The best base layers and underwear, reviewed and curated by the Trailspace community. The latest review was added on February 27, 2023. Stores' prices and availability are updated daily.

user rating: 5 of 5 (1)
Ibex Woolies Tech Bottoms Bottom
$81
user rating: 5 of 5 (1)
Smartwool Merino Boxer Brief Boxer/Brief/Bikini
$19 - $134
user rating: 5 of 5 (1)
Fjallraven Bergtagen Woolmesh Sweater Top
$106 - $111
user rating: 5 of 5 (2)
Voormi River Run Hoodie Top
$129
user rating: 4.5 of 5 (9)
ExOfficio Give-N-Go Boxer Brief Boxer/Brief/Bikini
$12 - $29
user rating: 4.5 of 5 (1)
Patagonia Capilene Air Bottoms Bottom
$76 - $265
user rating: 4.5 of 5 (1)
Outdoor Research Enigma Bottoms Bottom
$48
user rating: 4.5 of 5 (1)
Smartwool Classic All-Season Merino Base Layer Bottom Bottom
$14 - $90
user rating: 4.5 of 5 (1)
Black Diamond Solution 150 Merino Base 3/4 Bottom
$100
user rating: 4.5 of 5 (1)
Black Diamond Solution 150 Merino Base Crew Top
$55 - $135
user rating: 4.5 of 5 (1)
Kari Traa Rose Long Sleeve Top
$77 - $110
user rating: 4.5 of 5 (1)
Smartwool Merino 150 Pocket Tee Top / Short Sleeve Performance
$64
user rating: 4.5 of 5 (1)
Patagonia Capilene Air Hoody Top
$87 - $159
user rating: 5 of 5 (2)
Patagonia R1 Pants Bottom / Fleece
$129
user rating: 5 of 5 (2)
Helly Hansen HH LIFA Stripe Crew Top
$45
user rating: 5 of 5 (1)
Minus33 Acadian Lightweight Boxer Brief Boxer/Brief/Bikini
$45
user rating: 4 of 5 (2)
Patagonia Capilene Air Crew Top
$52 - $129
user rating: 4 of 5 (2)
Outdoor Research ActiveIce Sun Sleeves Arm/Leg Sleeve
$18 - $57
user rating: 4 of 5 (1)
Smartwool Intraknit Merino 250 Thermal 1/4 Zip Top
$91 - $320
user rating: 4.5 of 5 (1)
Icebreaker Anatomica Brief Boxer/Brief/Bikini
$30 - $280
user rating: 4.5 of 5 (1)
Smartwool Merino Sport 150 Brief Boxer/Brief/Bikini
$18 - $25
user rating: 5 of 5 (1)
Patagonia Capilene 3 Midweight Bottoms Bottom
$20 - $126
user rating: 4 of 5 (1)
Outdoor Research Alpine Onset Crew Top
$49 - $99
user rating: 3 of 5 (2)
Patagonia Capilene Thermal Weight Zip-Neck Top
$65 - $109
user rating: 3.5 of 5 (1)
Outdoor Research Alpine Onset Bottoms Bottom
$40 - $194
user rating: 3.5 of 5 (2)
ExOfficio Give-N-Go Boxer Boxer/Brief/Bikini
$17 - $29
ExOfficio Sol Cool Boxer Brief Boxer/Brief/Bikini
$25
user rating: 3 of 5 (1)
Minus33 Isolation Midweight Merino Zip-Neck Top
$100
Airblaster Ninja Suit One-Piece Base Layer
$38 - $1,012
user rating: 2 of 5 (1)
Terramar Silk Pant Bottom
$40 - $60
user rating: 5 of 5 (1)
Fjallraven Bergtagen Longjohns Bottom
$140 MSRP
user rating: 5 of 5 (1)
Patagonia Merino Air Bottoms Bottom
user rating: 5 of 5 (1)
Patagonia Merino Air Hoody Top
user rating: 5 of 5 (1)
Ridge Merino Inversion Heavyweight Crew Top
$90 MSRP
user rating: 5 of 5 (6)
Patagonia Capilene 2 Lightweight Zip-Neck Top
user rating: 4.5 of 5 (3)
Smartwool Microweight Tee Top
$65 MSRP
user rating: 4.5 of 5 (1)
Outdoor Research Enigma Boxer Briefs Boxer/Brief/Bikini
$34 MSRP
user rating: 4.5 of 5 (1)
Ridge Merino Inversion Midweight Bottoms Bottom
$50 MSRP
user rating: 4.5 of 5 (1)
Helly Hansen HH Lifa Merino Pant Bottom
$90 MSRP
user rating: 4.5 of 5 (1)
Outdoor Research Enigma Half Zip Top
$79 MSRP
user rating: 4.5 of 5 (1)
Appalachian Gear Company All-Paca Crew Long Sleeve Performance Top / Top
$145 MSRP
user rating: 4.5 of 5 (1)
FORLOH Deep Space Half Zip Long Sleeve Top Top
$129 MSRP
user rating: 4.5 of 5 (1)
Smartwool Microweight Bottom Bottom
$70 MSRP
user rating: 4.5 of 5 (1)
Helly Hansen HH Lifa Merino 1/2 Zip Top
$100 MSRP
user rating: 4.5 of 5 (1)
Smartwool Midweight Funnel Zip Top
$100 MSRP
user rating: 4.5 of 5 (1)
Kari Traa Rose Pant Bottom
user rating: 5 of 5 (3)
Icebreaker Bodyfit 150 Long Sleeve Crewe Top
user rating: 5 of 5 (1)
Adidas Sport Performance Flex 360 Boxer Brief Boxer/Brief/Bikini
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Recent Base Layer Reviews

rated 5 of 5 stars
Ibex Woolies Tech Bottoms

Versatile lightweight merino blend layer, perfect for winter backcountry use, chilly nights in camp, and just lounging around at home on cold days. I’ve been a huge fan of Ibex clothing for many years. The Ibex Indie hoody I bought probably twenty years ago, is still one of my favorites. I was sad when they announced that they were closing a number of years ago and have been pleased to see that they have returned. I was eager to give these bottoms a try. I received the Woolies Tech Bottoms in… Full review

rated 1.5 of 5 stars
Isobaa Merino 200 Zip Neck Hoodie

Ordered two t shirts size L. One of them had L on top tag but inside was XL—other was real L. Shop mistake. But I realised XL seems to fit better on me. I contacted them with request how can I replace the L for XL. They gave me return address and asked me to order another one and promised refund. I’ve sent it by Royal Mail Class 2 and 4 weeks after—there’s no refund. Email answer is copy/paste: Our records show the return has not been processed by our warehouse yet. Returns can take up to… Full review

rated 4.5 of 5 stars
Smartwool Classic All-Season Merino Base Layer Bottom

A full-length base layer bottom that has real value on trail in all four seasons. Smartwool's Classic All-Season Merino Base Layer Bottom uses a 150g wool/nylon blend fabric that is heavy enough to add warmth when layered but light enough to use as a hiking tight in warm weather. Comfort and durability for use all year.   Taft Lodge on the Long Trail (Vermont) Long a fan of Smartwool layers in winter, I spent this summer testing some of their gear that works well in warm weather. Along with the… Full review

rated 2.5 of 5 stars
Isobaa Merino 200 Zip Neck Hoodie

Great fit and style, but not durable and less technically advanced material. The look and fit is great. But, the material itself is far less durable than other merino shirts I own from Icebreaker or Ortovox. It gets holes quite easily and also is a bit more sweaty.  Full review

rated 5 of 5 stars
Smartwool Merino Boxer Brief

Smartwool brings Merino magic with their Boxer Brief. Comfortable, functional, and surprisingly durable these are great for any sort of hiking or backpacking, but especially useful on extended trips when you appreciate the no-stink qualities of good wool.   . I have had great experience in the past with Smartwool products having enjoyed their socks and insulating layers. When the chance came up to test their Merino Boxer Brief I had high expectations. Made with a Merino/nylon blend, 150g weight… Full review

rated 1 of 5 stars
Isobaa Merino 200 Zip Neck Hoodie

I don’t recommend even being cheaper than other brands. I think it is worth paying a little more for a quality brand that lasts a long time.             I have a couple of garments of this brand and I am very unhappy with the quality. Merino wool has features like durability, warmth, or that does not smell. I have had merino clothes since years but Isobaa is, by far, the worst quality. After one year using a hooded jacket, the cuffs are shattered with holes and the general aspect is very… Full review

rated 5 of 5 stars
Voormi River Run Hoodie

A super-comfortable and versatile Merino blend hooded shirt, excels as a sun or wind shirt. This is the first time I’ve really tried a long-sleeved sun protective shirt, and I was pleasantly surprised how comfortable it is in warm conditions. Though it is marketed as a sun shirt, it is much more than that.   Morning walk in the foothills Having read several super positive reviews about this hoodie, I wanted to give it a try, but was put-off a little bit by the price tag. But having recently moved… Full review

rated 5 of 5 stars
U.S. Military Gen III, Level 2 ECWCS Top

I agree. Great layer. I live in Colorado and use this Level 2 layer—I agree with the other reviewer. You just have to make sure you are getting the authentic Polartec fabric version spec. Needs to have Polartec tags. Full review

rated 5 of 5 stars
Helly Hansen HH LIFA Stripe Crew

A classic go-to for late autumn-winter-early spring. Tough as nails and a very practical change from wool and other fibres. My “cold weather” (similar to Lester’s) version is now 10 years old and doesn’t show any signs of giving up the ghost. I will say it’s comparable to wool. Not the same AS wool but if you can find a man-made fibre shirt that is known around the world for its quality and practicality, and durability then please let everyone know. When humping a pack, I tend to wear… Full review

Other Types of Clothing and Accessories

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