Crack climbing is a type of rock climbing in which the climber follows a crack in the rock and uses specialized climbing techniques. The sizes of cracks vary from those that are just barely wide enough for the fingers to fit inside, to those that are so wide that the entire body can fit inside with all limbs outstretched. Many traditional climbing routes follow crack systems, as they provide natural opportunities for placing protective equipment.
Widths
In the context of climbing, cracks are classified by their width in relation to the climber's body: finger, off-finger, hand, off-width, and chimneys. Finger cracks are just wide enough for all or part of the finger to fit inside; this width incorporates techniques used in face climbing and tends to favor climbers with small hands. Off-finger cracks are wider than finger cracks, but not large enough for the entire hand to fit inside. Hand cracks are just large enough for the entire hand to fit inside; the techniques for this width are "readily learned and very secure". Off-width cracks are wider than hand cracks, but not wide enough for the entire body to fit inside; this width requires movements that can be physically awkward or uncomfortable. Chimney cracks are large enough to fit the entire body inside, allowing for a wide variety of techniques depending on the distance between the two rock faces.
The walls of crack systems rarely run parallel to each other throughout the entire length of the crack; they frequently constrict inwards and open outwards in various places. Some of the most challenging climbs follow cracks which run through many different widths. Even when a crack is uniform in width, it may require a different approach for each individual climber—a hand crack for a smaller climber may be an off-finger crack for a larger climber.
History
Throughout the history of rock climbing, whenever traditional climbers seek to develop routes in a new area, they almost invariably follow crack systems that offer natural locations for placing protective equipment. The use of the term "line" as a synonym for "route" derives from this practice, as cracks often form visually distinct lines that can be followed from base to top.
Prior to the introduction of spring-loaded camming devices, there was no suitable method for placing protective gear in cracks wider than a few inches, which made such routes extremely dangerous even when they were not technically demanding. It was not until the 1980s that camming devices proliferated, enabling climbers to ascend more crack systems safely.
By the 1990s, crack climbing had diminished in popularity for a variety of reasons. The advent of sport climbing allowed climbers to focus on difficulty and aesthetic appeal when developing new routes; it was no longer necessary to learn specialized crack techniques in order to lead climb safely. Furthermore, cracks are difficult to simulate in climbing gyms, so those who train indoors are limited to face routes when they climb outside.
In 2006, Canadian Sonnie Trotter made the first free ascent of the Cobra Crack (5.14b) in Squamish, British Columbia, which at the time was considered to be the hardest crack climb in the world. Since this ascent, new and perhaps more difficult crack lines have been climbed including Stranger than Fiction (5.14b) in Canyonlands National Park, The Meltdown (5.14c) in Yosemite National Park, Blackbeard's Tears (5.14c) on the California coast and The Recovery Drink (5.14c) in Norway's Jossingfjord.
In 2011, Tom Randall and Pete Whittaker completed the first free ascent of Century Crack (5.14b), a off-width in Canyonlands National Park, Utah. The crack was first attempted in 2001 and is considered the hardest off-width crack climb in the world.
In 2015, Tom Randall completed the first free ascent of The Kraken, in Devon, England. At V13, it is considered the hardest crack boulder in the world, and has only been repeated once.
Technique
The most fundamental technique used in crack climbing is "jamming", in which the climber forces a body part into the crack such that it exerts force on both walls. This creates the friction needed for the climber to make upward progress. The body part used and its positioning are largely dependent on the width of the crack. For example, some cracks are just wide enough that they can be jammed with an open hand. A crack slightly wider than that may require the hand to be curled into a fist to form an effective jam.