One of the most popular mountaineering socks of all time from Smartwool.  These extra thick socks provide warmth for cold weather outings, as well as lots of cushion to help pad and protect your feet when traveling in difficult mountainous terrain or carrying a heavy pack.  Thick socks like these also help make your boots fit and feel better by filling in the voids where you need to in order to customize the fit of your boots.  Always save a fresh dry pair of these socks in your pack for your summit day.