Smartwool Mountaineering Extra Heavy Crew Socks

Size Chart
Charcoal Heather

Go the distance in the Smartwool Mountaineering Extra Heavy Crew Socks. Durable, streamlined construction and designed for mountaineering or multi-day backpacking, the Smartwool Mountaineering Extra Heavy Crew Sock provides full support and shock absorption for intense, all-day use.


  • Height: Crew
  • Cushion: Heavy
  • Flat Knit Toe Seam for superior comfort
  • Evaporates and Wicks Moisture
  • Smartwool fit system with arch and ankle support
  • Anti Odor
  • Made in the USA of imported yarn


74% Merino Wool, 25% Nylon, 1% Elastane

Sock Height

Crew Height Sock

Sock Cushion

Extra Heavy Cushion Sock

Customer Reviews

Based on 21 reviews
Best socks ever made

These are literally the best socks ever made. I started wearing Smartwool socks 15 years ago due to an injury from Dessert Storm. This will be the first time I've replaced them in 15 years. People will say to me "You pay $20.00 for a pair of socks?" So let's average that out, $20.00 divided by 15 years equals $1.33 a year. Personally I think that is a very good price for the best sock ever made. I wear them around them around the house for slippers (that alone should wear them out), then I wear them 9 hours a day during the week to the construction site (that is winter and summer - wool is the only product that works as well in the summer as the winter - and I don't get athletes foot nor do my feet burn up in the 100 degree weather), then on the weekends for every other outdoor activity that you can think of where you would wear boots. Nothing could possibly exceed these socks - Thank You Smartwool for your excellent craftsmanship !!!!!!!!

j s. (Dickinson, North Dakota)
Runs larger than stated size & some noticeably early fraying, but still are thick & warm

I like the thickness of the material. However, I noticed that, though I picked the correct size indicated for my shoe size, the actual socks I received are for feet three or four shoe sizes bigger. For me, the fit of this sock is too baggy. If I was in need of a thick (slightly thicker than the thickest Darn Tough) and warm sock, I'd consider Smartwool Mountaineering Extra Heavy Crew Socks; I would, however, order the next smaller size down, since the size designated on the tag seems too big.

The other thing is, I noticed the material developed a lot of little 'fuzzies' and a few of the threads came noticeably loose (this after one wash!). I washed them in a gentle wash cycle and did not over dry it. I did not notice such thread fraying with my normal brand, Darn Tough. So, to me, Smartwool isn't as durable as Darn Tough.

Ellen Ackerman (Santa Fe, New Mexico)
Sizes run big

These socks run bigger than others I have gotten from GoBros. I have metatarsalgia in my feet, so must have socks that don't bunch up in my shoes. This is why I buy from GoBros, to get tight socks. But these bunched up and caused excruciating pain. I'm sending them back to be replaced with a smaller size, and hope that works. I'm not happy that I have to pay shipping on returns.

Carrie P.
Smart wool heavy socks

I really like these thick socks. I bought them to wear while watching wildlife in Yellowstone NP. They washed up nicely and are true to size. I like that they come up higher on my legs too.

Alicia S.
Highly recommend

Great socks. I have had these before and I came back for more. What else is there to say? And yes I will recommend this product to others. Thanks again......