Mountaineering boots are a type of footwear used in the sport

Extreme sport

An extreme sport is a popular term for certain activities perceived as having a high level of inherent danger...

 of mountain climbing. They are designed specifically for moving over harsh terrain.

Design

Not to be confused with hiking boots, mountaineering boots are usually taller, stiffer, and insulated. The boots can be made of leather

Leather

Leather is a durable and flexible material created via the tanning of putrescible animal rawhide and skin, primarily cattlehide. It can be produced through different manufacturing processes, ranging from cottage industry to heavy industry.-Forms:...

, plastic

Plastic

A plastic material is any of a wide range of synthetic or semi-synthetic organic solids used in the manufacture of industrial products. Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance and/or reduce production costs...

, or modern synthetic materials like Kevlar

Kevlar

Kevlar is the registered trademark for a para-aramid synthetic fiber, related to other aramids such as Nomex and Technora. Developed at DuPont in 1965, this high strength material was first commercially used in the early 1970s as a replacement for steel in racing tires...

.

The extra height and stiffness of mountaineering boots helps support the climber in steep terrain where flexible boots could cause unsure footing and possibly result in a fall. This extra stiffness is traditionally achieved through the use of a full steel shank

Shank (footwear)

In a boot or shoe, the shank is a part of the supportive structure between the insole and outsole. The presence of a shank is crucial to the functionality of mountaineering boots as they diminish the load incurred by the wearer’s feet and calves over the course of an ascent...

, though some manufacturers have begun to use carbon fiber

Carbon fiber

Carbon fiber, alternatively graphite fiber, carbon graphite or CF, is a material consisting of fibers about 5–10 μm in diameter and composed mostly of carbon atoms. The carbon atoms are bonded together in crystals that are more or less aligned parallel to the long axis of the fiber...

 to create the necessary stiffness.
Mountaineering boots are typically designed to be used with crampons

Crampons

Crampons are traction devices used to improve mobility on snow and ice. There are three main attachment systems for footwear: step-in, hybrid, and strap bindings. The first two require boots with welts, the last adapt to any type....

. To achieve compatibility with crampons, welts are molded into the toe and heel of the boot, providing a platform for the crampon to attach to. The stiffness of the boot enhances the precision of the crampon and allows a climber to pursue steeper and more difficult terrain.

Another important aspect of mountaineering boots is warmth. To prevent frostbite

Frostbite

Frostbite is the medical condition where localized damage is caused to skin and other tissues due to extreme cold. Frostbite is most likely to happen in body parts farthest from the heart and those with large exposed areas...

 in extreme cold conditions, synthetic insulation is incorporated into the boot. Lighter weight boots are classified as single boots. These single boots are insulated as a single unit with the insulation being permanently attached to the rest of the boot. Double boots, another classification, typically consist of a non-insulated shell with a removable insulated liner. They have either a leather or plastic outer-shell as well as a removable liner. The purpose of a double boot is long term protection from cold weather. If the liner becomes wet, it can be removed from the shell and dried inside a sleeping bag

Sleeping bag

A sleeping bag is a protective "bag" for a person to sleep in, essentially a blanket that can be closed with a zipper or similar means, and functions as a bed in situations where a bed is unavailable . Its primary purpose is to provide warmth and thermal insulation...

. Since the insulation cannot be removed from single boots, they are not ideally suited for multi-day cold weather excursions.

Other uses

Mountaineering boots are used for ice climbing

Ice climbing

Ice climbing, as the term indicates, is the activity of ascending inclined ice formations. Usually, ice climbing refers to roped and protected climbing of features such as icefalls, frozen waterfalls, and cliffs and rock slabs covered with ice refrozen from flows of water. For the purposes of...

, mixed (rock & ice) climbing

Climbing

Climbing is the activity of using one's hands and feet to ascend a steep object. It is done both for recreation and professionally, as part of activities such as maintenance of a structure, or military operations.Climbing activities include:* Bouldering: Ascending boulders or small...

, and crevasse

Crevasse

A crevasse is a deep crack in an ice sheet rhys glacier . Crevasses form as a result of the movement and resulting stress associated with the sheer stress generated when two semi-rigid pieces above a plastic substrate have different rates of movement...

 traverse and rescue

Crevasse rescue

Crevasse rescue is the process of retrieving a climber from a crevasse in a glacier. Because of the frequency with which climbers break through the snow over a crevasse and fall in, crevasse rescue technique is a standard part of climbing education....

. They are not completely stiff like ski boots as they need some degree of flexibility for activities such as hiking

Hiking

Hiking is an outdoor activity which consists of walking in natural environments, often in mountainous or other scenic terrain. People often hike on hiking trails. It is such a popular activity that there are numerous hiking organizations worldwide. The health benefits of different types of hiking...

 and snowshoeing.

The versatility of these boots also makes them popular for other activities. With their durability and extreme-weather adaptability, they are worn by snow-plough drivers, cable car operators, mountain rangers (especially in the winter), rescue paramedics, ski lift operators and snowcat

Snowcat

A snowcat is an enclosed-cab, truck sized, fully tracked vehicle designed to move on snow. Snowcats are often referred to as 'trail groomers' because of their use for grooming ski trails or snowmobile trails...

 drivers.

Mountaineering boots are generally considered to be too stiff for backpacking

Backpacking (wilderness)

Backpacking combines the activities of hiking and camping for an overnight stay in backcountry wilderness...

on established trails.