Extremely warm and durable, the Patagonia Heavyweight Mountaineering Socks stymie the raw temps of skiing, ice climbing and cold-weather mountaineering. Tightly knit from a blend of 75% merino wool (chlorine-free) for warmth, they also have 12% nylon, 10% polyester and 3% spandex to balance durability and wicking performance. Soft, felted merino wool yarns throughout cushion, insulate, and last the lifetime of the sock.

Tested and recommended by GORE-TEX® labs for hiking shoes and climbing boots equipped with GORE-TEX® textiles, the Bridgedale Expedition Summit Sock is comfort rated to -13F (-25C). The design is very similar to Bridgedale's bestselling Summit sock, but the Expedition Summit Sock has a special Y-heel and anatomic foot shape, extra length and plenty of double-density padding under the foot. This is a design developed for extended wear in those cold spaces where the nearest warming hut or refuge is hundreds of miles away. Whether you're trekking into uncharted territory or just looking for gaiter-length warmth for your winter backcountry fun, the Bridgedale Expedition Summit Sock is one of the best for cold weather protection.

Designed to keep your feet warm in even the coldest conditions, the Icebreaker Mountaineer Mid Calf Socks for Women are constructed with extra heavy cushioning zones to provide maximum protection, warmth and comfort.

Designed to keep your feet warm in even the coldest conditions, the Icebreaker Mountaineer Mid Calf Socks for Men are constructed with extra heavy cushioning zones to provide maximum protection, warmth and comfort.

The Bridgedale Midweight Control Fit Socks for Men offer a warm and comfortable toe box shaped to reduce volume. Friction-Free zones provide easy entry into tight fitting performance boots. Light compression is graduating up the leg to help improve comfort and aid in circulation. Tapered triple-density shin padding protects the shin without bulk.

The Bridgedale Controlled Fit Socks for Women are Bridgedale's closest fitting performance sock for women featuring a friction free heel and ankle for easy boot entry. Anatomically mapped to match women's leg and foot shapes and fearturing a 360 degree wrap of triple density cushioning to comfort the upper leg.

Tested to -13 degrees Fahrenheit (-25 degrees Celsius), the Bridgedale Men's Endurance Summit Sock is the warmest and most cushioned sock by Bridgedale. Perfect for year around mountain expeditions and extended outdoor pursuits, this heavyweight sock features high density yarn throughout the foot to provide extra protection and impact resistance. Bridgedale's unique Woolfusion® technology yarn blends a high content of moisture absorbing New Wool with wicking Endurofil™. This pulls excess moisture away from the foot ensuring lasting comfort and blister control. Targeted knitting around the ankle defines a deep heel pocket and easy ankle flex zone to maintain a precise fit. The sculpted heavyweight cushioning provides extra comfort and protection in the Achilles-heel and toe box area. The men's Bridgedale Endurance Summit Sock is designed for use with full-height high volume footwear in cold conditions.

Ideal for a climb of Mount Rainier, or that trip-of-a-lifetime trek in the Himalayas, the SmartWool Mountaineering Xtra Heavy Mid-Calf sock bathes your feet in high altitude comfort. The unique SmartWool fibers have the ability to keep feet warm and dry when the temperature drops and perspiration free when the temperature rises. This is due to the fiber's fast moisture moving characteristics, transporting water before it condenses while still in the vapor stage. The SmartWool Mountaineering Xtra Heavy Mid-Calf sock not only cushions the bottom of the foot, but the top of the foot too. This aids in protecting the foot from pressure caused by stiff boot uppers, crampon straps, and impact from kicking steps up long couloirs. Another feature of great value is the arch and ankle bracing - areas of increased spandex content to comfortably hug the foot and eliminate sock movement and bunching. After all, the last thing you want to worry about is an annoying wrinkle in your socks buried within your boots, crampons, and gaiters.

Wool: your new best friend. These socks will keep you on the trail in comfort. Full wicking and moisture management capabilities and the durable performance of Smartwool will keep you from going back to your old socks.

The Bridgedale All Mountain Socks for Women are the warmest and thickest women's sock for skiing, boarding and alpine touring with a new snowflake pattern on the back calf. A heavy weight sock ideal for recreational activies.

Designed with heavy cushioning throughout, the Icebreaker Hiker Heavy Crew Socks for Women are constructed with strategic reinforcement zones to ensure maximum support, warmth and moisture management.

A great choice for summer mountaineering trips or other adventures involving colder temperatures, the SmartWool Trekking Heavy Crew sock provides a haven of comfort for your feet. Heavy full cushioning surrounds the foot, a nice buffer to have when wearing the heavier, stiffer footwear usually associated with extended alpine excursions. The SmartWool fibers also have a lot to do with the fabulous comfort experienced in the SmartWool Trekking Heavy Crew sock. They have a very small micron diameter, between one-tenth and one-third the size of a human hair, making for a very soft, comfortable feel. And equally important, these same fibers move perspiration moisture at a fast clip, even while still in the vapor stage so the feet stay dry throughout the day.