Plastic boots have a hard plastic outer shell, and a durable and removable synthetic inner boot. This double-boot model is great for all alpine climbs, expeditions and multi-day situations because the inner boot can be removed and dried overnight. While plastic boots are waterproof, protecting your foot from snowmelt, stream crossings and glacial pools, etc., the inner boot will still become wet from sweat. Still, plastic boots are the warmest footwear. Some are outfitted with knee-high gaitors—an expensive set up normally reserved for 8,000-meter peak-bagging. Plastic boots are generally very stiff, which makes them great crampon bearers. Strap-on crampons work well with plastic boots because the straps can be cinched very tight, without affecting circulation to your lower extremities. Plastic boots perform well at ice and mixed crags, too, but not nearly as well as lighter leather or synthetic boots.
Every serious climbing-boot maker has one or more boots with a synthetic, or partial synthetic, upper. This breed of mountaineering boot is lighter and more comfortable (with a shorter break-in time) and dries faster than all-leather footwear. Disadvantages? Synthetic materials can make a boot softer (less supportive on steep ice) and can be less durable than all leather, although unless you practically live in your boots you’ll likely never wear them out. The trend is for all-synthetic boots and with each passing season these designs get better and better, smartly blending stiff plastics with softer fabrics, and are not to the point of being the standard rather than the exception.
Leather mountaineering boots have withstood the test of time and virtually every breakthrough climb, from Everest to K2, to Cerro Torre to Denali, was accomplished by climbers shod in leather. Leather boots are tough, stiff and solid enough to withstand the jagged harshness of ice, rock and snow, yet often comfortable enough to hike in all day. Make sure your leather boot has: a high enough upper to support your ankle, a good lug sole, toe and heel welts, a stiff shank to help with frontpointing, and a hard toe and heel to protect your foot from kick and plunge steps. Leather boots are often light enough to climb technical rock—make sure they fit well so you can edge with them.
Choosing the stiffness of a boot depends on the technical difficulty you are interested in pursuing. You won’t need a rigid boot for exploring glaciers, and you wouldn’t want a flexible boot for heading up the 1,200 feet of vertical ice of Quebec’s Le Pomme d’Or.
The most rigid boots, such as plastic boots and extremely stiff leather boots, are most at home on technical ice routes. When your entire body weight is on two front points shoved an inch into a flow of ice, your calves will appreciate the stiffness of a rigid boot. Hiking across moraines and along other rugged trails is, of course, possible in the most rigid boots, but takes some getting used to. You will have to learn how to heel-toe up to the technical bits. Not ideal, but the choice of many climbers.
These boots are best for less demanding snow and ice routes. They will provide enough support for standing in aiders, climbing cracks and lower-angle ice, while allowing for an increased degree of comfort. Both leather and synthetic boots work well in these situations, as long as the sole is firm and the upper provides support above the ankle. These boots can also be used on alpine rock climbs, where you’ll be jamming your foot into cracks. However, don’t expect to climb at your rock on-sight level.
The most flexible boots are for trekking through snow and ice, stream and talus. This footwear is not going to be at home on more technical routes, but your dogs won’t be barking at the end of a long day. Flexible boots should pair with flexible crampons. These boots will work well on easy approaches. They are often light, which can mean the difference between reaching camp before dark or not.
Technical boots will have a deep toe and heel grove just above the upper edge of the sole. This is to secure a step-in crampon with a toe bail and a heel bail with a tensioning lever.
IT IS CRITICAL THAT YOU TEST YOUR CRAMPONS ON YOUR BOOTS BEFORE YOU BUY. Unlike ski bindings which are universal and conform to the same DIN standard, crampon bindings vary drastically from one model or company to the other. Some crampons, due to their shape or height or thickness of the bail won’t work on some boots—they’ll pop off under the stress of frontpointing. This is a big problem that manufacturers are only now beginning to address; some offer different bails for different models of boots.
Many models of crampons have hybrid bindings, with a plastic or nylon toe piece that wraps up and over the boot toe, and only have a heel bail. These crampons are meant for less technical climbing, such as snow mountaineering and glacier travel, where the crampon doesn’t need to fit super snug and a bit of crampon wobble isn’t a concern. Crampons with hybrid bindings don’t require a stiff boot or a grooved toe welt.
Many boots meant for extreme high-altitude conditions of cold, and some top-end technical boots, have integrated gaiters. Building a gaiter into the boot saves weigh because lets the gaiter become part of the boot’s structure, and provides the best weather-tight seal against snow and water. The disadvantages are that they zipper can break (keep it clean and lubricated), necessitating an expensive repair (if you are fortunate enough to have the zipper blow out at home), and the gaiter adds an additional layer of expense to the boot.