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Smartwool - Mountaineering Extra Heavy Crew Sock

Smartwool Mountaineering Extra Heavy Crew Sock

45% Off
$13.72 Original price:$24.95
Changing the size selection, or changing the selected color after selecting a size, may change the associated price

Item #SWL005L




Tech Specs

74% merino, 25% nylon, 1% elastane
extra heavy
Recommended Use:
backpacking, hiking, mountaineering, trail
Manufacturer Warranty:
2 years

Mountaineering Extra Heavy Crew Sock

When you're high up on the mountain, the last thing you want to worry about is your feet. Wear the Smartwool Mountaineering Extra Heavy Crew Sock, and focus all of your energy on bagging that summit. This crew-length sock utilizes Smartwool's wool-on-wool technology for maximum extra-heavy cushioning and durability. A flat-knit toe seam helps to avoid irritation inside your boot, and Smartwool's fit system gives added arch and ankle support. The natural anti-odor properties of merino wool fend off funky odors from interfering with your expedition.

  • Crew socks offer heavyweight cushioning for mountaineering and hiking
  • Integrated arch-brace holds the sock in place during long trekking days
  • Heaviest cushioning in the line keeps your feet warm in poor weather
  • Natural anti-itch properties of merino wool keep your feet comfortable

The Warmest Sock EVER?

  • Familiarity: I've put it through the wringer
  • Fit: True to size

I run cold, like really, really cold. I got tired of spending my entire paycheck trying to heat my basement apartment, so I went on a search for the warmest socks on planet Earth. Are these truly the warmest on the planet? I don't know, but I can surely say these are soooo toasty. The cushioning is divine and they keep my feet from feeling like total ice cubes. I love that they're breathable, too. I m going to get more pairs to take camping in the fall. If you're going to be outside in the winter, make sure these are in your quiver. If you wanna go hard on warmth, I would pair these with the Rab hut slipper or bootie.

Trust me, I have been searching high and low and have purchased well over 20 pairs of socks and these blow the rest out of the (ice)water.

Thank me later.

My sleeping socks

  • Familiarity: I've put it through the wringer
  • Fit: True to size
  • Size Bought: L

I love sleeping with these on during the winter trips

Changed the fit and weight

    I have several pairs of these going back years . The new style I see has a very tight opening were you slide the foot they also have cut back on the weight and length

    Super Warm!

    • Familiarity: I gave it as a gift but have feedback to share

    Got these socks for my boyfriend this winter to use ice fishing and boy they do their job. These socks are a lot thicker than I was expecting, for some reason but I am so glad they are. He says these socks are the absolute best and he can't believe he can still feel his toes after being on the ice for hours.


    • Familiarity: I've used it once or twice and have initial impressions

    Super warm and thick socks but I'd size down. I wear a size 46 mountaineering boot and have the large size socks. My feet are swimming in them and they sag a LOT.

    Warm and Comfortable

    • Familiarity: I gave it as a gift but have feedback to share

    I bought these as a gift for a friend and this is what he had to say:
    "I wanted these for fly fishing in the winter to pair with the Patagonia Winter Weight Fleece Oversock and they’ve made the ultimate pair for keeping my feet warm when I’m fishing in the the winter. They’re very thick and super comfy for long days on the water"


    • Familiarity: I've put it through the wringer

    These are the best sock for your mountaineering boots or if your ski boots are very packed out. They are high enough so you don't have rubbing on your shins.

    Best Sock for Skiing!

      These are by far the best socks for your winter activities. They are nice and padded and provide plenty of warmth. The socks do seem to last forever. Amazing!

      Great for Cold Weather

      • Familiarity: I've put it through the wringer

      These socks are great, they do just what they are supposed to keeping your feet warm in cold temperatures. They are extremely soft and are very comfortable to wear on your feet, they are a little bulky so footwear with a little extra space can make things a little more comfortable, I've squeezed them into tighter pair so boots and they still work well just maybe not for really long days. The only issue I have with these is that the top of the sock tends to cut into my calves a bit because of the string/elastic at the top and the fact I have pretty large calves, but i can look past this due to the warmth these provide. They are also great for cold winter days inside on non-carpeted surfaces.


        If you are looking for warmth, look no further. These socks keep your feet toasty no matter what the conditions. The only disclaimer would be that they are a little bulky, so be aware of that when deciding what boots/shoes you will be wearing these with.

        Cozy Wonderland for Your Feet

        • Familiarity: I've put it through the wringer

        I freaking love these socks! When my feet are feeling cold, I put these on, and my feet are nice and toasty within 5 minutes. These are also the only socks I will wear ice climbing. I have been out in sub-freezing temperatures for 8+ hours while ice climbing, and my feet stayed warm the whole time. I also wear these around the house as slippers. I always bring these on long flights as well, because they are so so so comfortable.

        These are very well made and durable. I have had my first pair for over a year. I have washed them numerous times, and they are still holding up great. But they do seem to be thinning out a bit (I seriously have worn them several times a week for over a year now, so that is understandable). I just bought another pair of these for this winter, and I cannot wait to use them.

        Worth the dough

        • Familiarity: I've used it several times

        Very comfortable and very warm, you can wear them under 40 degrees if you are a hot body and under 50 if you are a cold bodied person. They wash well and have held up under multiple washes and many miles of hiking. Long term is uncertain but I have had multiple of their products before that speak for themselves. $24 is a steep price but its worth it, especially if you can get it on sale.

        Quality- 10/10
        Comfort- 10/10
        Cost- 7.5/10
        Practicality- 9/10
        Value- 9/10
        My final conclusion is that I would recommend them and nothing better is on the market that I've found.

        Thick, warm and high quality

        • Familiarity: I've used it once or twice and have initial impressions

        What more do you need in great socks? These are well made and do exactly what they should. The elastic is nice and they seem like they will last a long time.

        Coziest Socks Ever!

        • Familiarity: I've put it through the wringer

        In trying to follow the Danish concept of Hygge, I bought these socks to embrace all that is cozy! These are the plushest socks I could find and I absolutely love them! They are super warm and the heavy padding gives your feet the sweet relief they deserve. Do yourself a favor and get these socks, you will not be disappointed.

        Learn More: Smartwool Classic Hike Socks

          Learn more about the comfort, fit, and durability of Smartwool Classic Hike socks. #gofarfeelgood

          Doesn't Get Better

          • Familiarity: I've put it through the wringer

          Bought these for my wife and I don't think there has been one day since I bought them for her that she has not worn that for at least part of the day. Incredibly warm and comfortable while also durable and long lasting. We've tried tons of different types of warm socks in the past and no one has been able to compare to smartwool.

          Simply Awesome Socks

          • Familiarity: I've used it several times

          I can't say enough how great these socks are. Extremely comfortable, very warm and does a great job of keeping your feet dry even if your feet start to heat up a bit.

          That's a thick sock

          • Familiarity: I've put it through the wringer

          If you are looking for a pair of thick wool socks that will keep your feet warm look no further. These pair well with any winter boot to keep the wet, cold winter out and the heat in. Wear them around the house and they double as a light slipper. I was so impressed by the softness and the warmth I bought a couple of pair for gifts. I love Smartwool socks for their durability, and these continue the tradition. Strong, warm socks for any chilly day.

          Don’t forget your boots!

          • Familiarity: I've put it through the wringer

          I am a Smartwool diehard, had many pairs of most styles, but these are the best. They are insanely thick and warm. You might have to loosen the laces on your kicks to slip your feet in with these socks on. I have walked around camp in the snow with out my boots in these socks, that is how thick and warm they are! Killer around the house on winter mornings on the hardwoods too.


          • Familiarity: I've put it through the wringer

          These socks did a very nice job keeping my feet warm during the winter . I had no trouble walking around all day. The socks are very soft and provide cushion and support, I had no trouble with blisters or any discomfort. The moisture control kept my feet dry throughout the day.more pairs and recommended it to friends as well.


          US MEN 3 - 5.5 6 - 8.5 9 - 11.5 12 - 14.5
          US WOMEN 4 - 6.5 7 - 9.5 10 - 12.5  
          EU 34 - 37 38 - 41 42 - 45 46 - 49
          UK 2 - 4.5 5 - 7.5 8 - 10.5 11 - 13.5
          Calf Circumference

          11 - 14.5in

          (28 - 36.5cm)

          12.5 - 16.5in

          (32 - 41.5cm)

          14.5 - 18in

          (37 - 45.5cm)

          16 - 23in

          (41 - 58cm)

          US 6 - 8.5 9 - 11.5 12 - 2.5 3 - 6
          EU 22 - 25 26 - 28 29 - 32 33 - 36
          UK 5 - 7.5 8 - 10.5 11 - 13.5 1 - 4.5
          Use your shoe size to find your correct sock size.
          *Compression Socks and Calf Sleeves fit the same calf circumference as corresponding sock sizing.