To say that the summit of an 8,000-meter peak is cold would be an understatement. These sorts of high altitude expeditions are the reason why so many mountaineers have their toes treated for hypothermia, so make sure you wrap your foot in warmth that's as extreme as your expedition. Boreal comprised the G1 Expe Mountaineering Boot's super gaiter in waterproof, breathable Cordura fabric and plenty of EVA foam to keep hypothermia at bay, while the removable inner bootie boasts three layers of Thinsulate insulation that's wrapped in Boreal's waterproof, breathable Dry-Line so you can ditch the gaiter at basecamp. Boreal's carbon composite midsole keeps the boot stiff and surprisingly light, and two layers of EVA and PU add cushy comfort and shock absorption. Vibram's Betulla sole is an EVA rubber compound that keeps its grip in subzero temperatures.