Bouldering is a form of rock climbing that is performed on small rock formations or artificial rock walls without the use of ropes or harnesses. While bouldering can be done without any equipment, most climbers use climbing shoes to help secure footholds, chalk to keep their hands dry and to provide a firmer grip, and bouldering mats to prevent injuries from falls. Unlike free solo climbing, which is also performed without ropes, bouldering problems (the sequence of moves that a climber performs to complete the climb) are usually less than tall. Traverses, which are a form of boulder problem, require the climber to climb horizontally from one end to another. Artificial climbing walls allow boulderers to climb indoors in areas without natural boulders. Bouldering competitions take place in both indoor and outdoor settings.
The sport was originally a method of training for roped climbs and mountaineering, so climbers could practice specific moves at a safe distance from the ground. Additionally, the sport served to build stamina and increase finger strength. During the 20th century, bouldering evolved into a separate discipline. Individual problems are assigned ratings based on difficulty. Although there have been various rating systems used throughout the history of bouldering, modern problems usually use either the V-scale or the Fontainebleau scale.
Outdoor bouldering
The characteristics of boulder problems depend largely on the type of rock being climbed. For example, granite often features long cracks and slabs while sandstone rocks are known for their steep overhangs and frequent horizontal breaks. Limestone and volcanic rock are also used for bouldering.
There are many prominent bouldering areas throughout the United States, including Hueco Tanks in Texas, Mount Blue Sky in Colorado, The Appalachian Mountains in the Eastern United States, and The Buttermilks in Bishop, California. Squamish, British Columbia, is one of the most popular bouldering areas in Canada. Europe is also home to a number of bouldering sites, such as Fontainebleau in France, Meschia in Italy, Albarracín in Spain, and various mountains throughout Switzerland. Rocklands, South Africa is an additional notable site, one of the most popular in the world.
Indoor bouldering
Artificial climbing walls are used to simulate boulder problems in an indoor environment, usually at climbing gyms. These walls are constructed with wooden panels, polymer cement panels, concrete shells, or precast molds of actual rock walls. Holds, usually made of plastic, are then bolted onto the wall to create problems, or a sequence of bouldering moves to be overcome. Some problems use steep overhanging surfaces which force the climber to support much of their weight using their upper body strength.
Climbing gyms often feature multiple problems within the same section of wall. Historically, the most common method route-setters used to designate the intended problem was by placing colored tape next to each hold. For example, red tape would indicate one bouldering problem while green tape would be used to set a different problem in the same area. Indoor bouldering requires very little in terms of equipment: at minimum, climbing shoes; at maximum, a chalk bag, chalk, a brush, and climbing shoes.
Grading
Bouldering problems are assigned numerical difficulty ratings by route-setters and climbers. The two most widely used rating systems are the V-scale and the Fontainebleau system.
The V-scale (also known as the "Hueco" scale), which originated in the United States, is an open-ended rating system with higher numbers indicating a higher degree of difficulty. The V1 rating indicates that a problem can be completed by a novice climber in good physical condition after several attempts. The scale begins at V0, and as of 2024, the highest V rating that has been assigned to a bouldering problem is V17. Some climbing gyms also use a VB grade to indicate beginner problems.
The Fontainebleau scale follows a similar system, with each numerical grade divided into three ratings with the letters a, b, and c. For example, Fontainebleau 7A roughly corresponds with V6, while Fontainebleau 7C+ is equivalent to V10. In both systems, grades are further differentiated by appending "+" to indicate a small increase in difficulty. Despite this level of specificity, ratings of individual problems are often controversial, as ability level is not the only factor that affects how difficult a problem may be for a particular climber. Height, arm length, flexibility, and other body characteristics can also affect difficulty.
Highball bouldering Highball bouldering is "a sub-discipline of bouldering in which climbers seek out tall, imposing lines to climb ropeless above crash pads." It may have begun in 1961 when John Gill, without top-rope rehearsal or bouldering pads (which did not exist), climbed a steep face on an granite spire called The Thimble. In 2002 Jason Kehl completed the first highball at double-digit V-difficulty, called Evilution, a boulder in the Buttermilks of California, earning the grade of V12.
Important milestone ascents in this style include:
Ambrosia, V11, a boulder in Bishop, California, climbed by Kevin Jorgeson in 2015. Too Big to Flail, V10, another line in Bishop, California, climbed by Alex Honnold in 2016. The Process, V16, a boulder in Bishop, California, first climbed by Daniel Woods in 2015.
Competition bouldering
World Climbing employs an indoor format (although competitions can also take place in an outdoor setting) that breaks the competition into three rounds: qualifications, semi-finals, and finals. The rounds feature different sets of four to six boulder problems, and each competitor has a fixed amount of time to attempt each problem. At the end of each round, competitors are ranked by the number of completed problems with ties settled by the total number of attempts taken to solve the problems.
Some competitions only permit climbers a fixed number of attempts at each problem with a timed rest period in between. In an open-format competition, all climbers compete simultaneously, and are given a fixed amount of time to complete as many problems as possible. More points are awarded for more difficult problems, while points are deducted for multiple attempts on the same problem.
In 2012, the federation, then known as the International Federation of Sport Climbing, submitted a proposal to the International Olympic Committee (IOC) to include lead climbing in the 2020 Summer Olympics. The proposal was later revised to an "overall" competition, which would feature bouldering, lead climbing, and speed climbing. In 2016, the International Olympic Committee (IOC) officially approved climbing, along with four other sports, as an Olympic sport, based on their "impact on gender equality, the youth appeal of the sports and the legacy value of adding them to the Tokyo Games".
History
Modern bouldering Modern recreational climbing began in the late 19th century in England, southeastern Germany, northern Italy, and France. Bouldering on the rocks of Fontainebleau outside of Paris began in the late 1800s, with the first guidebook written by Maurice Martin in 1945. Bouldering as training or a recreational past-time began also in the late 1800s in England and perhaps elsewhere. Oscar Eckenstein was an early proponent.
In the late 1950s, John Gill, who is frequently called "the father of modern bouldering", combined gymnastics with rock climbing, and felt that the best place to do that was on boulders or small outcrops. He developed a rating system that was closed-ended: B1 problems were as difficult as the most challenging roped routes of the time, B2 problems were more difficult, and B3 problems had been completed once. He also introduced chalk as a method of keeping the climber's hands dry, promoted a dynamic climbing style, and emphasized the importance of strength training to complement skill. His 1969 article in the Journal of the American Alpine Club entitled "The Art of Bouldering" defines modern bouldering. As Gill improved in ability and influence, his ideas became the norm.
In the 1980s, two important training tools emerged. One important training tool was bouldering mats, also referred to as "crash pads", which protected against injuries from falling and enabled boulderers to climb in areas that would have been too dangerous otherwise. The second important tool was indoor climbing walls, which helped spread the sport to areas without outdoor climbing and allowed serious climbers to train year-round. As the sport grew in popularity, new bouldering areas were developed throughout Europe and the United States, and more athletes began participating in bouldering competitions. The visibility of the sport greatly increased in the early 2000s, as YouTube videos and climbing blogs helped boulderers around the world to quickly learn techniques, find hard problems, and announce newly completed projects.
Notable ascents
Notable boulder climbs are chronicled by the climbing media to track progress in boulder climbing standards and levels of technical difficulty; in contrast, the hardest traditional climbing routes tend to be of lower technical difficulty due to the additional burden of having to place protection during the course of the climb, and due to the lack of any possibility of using natural protection on the most extreme climbs.
As of February 2026, there exists one proposed , Exodia, by Elias Iagnemma, and fourteen boulders, ten of which have been repeated by at least one other climber. There are a number of routes with a confirmed climbing grade of , the first of which was Gioia by Christian Core in 2008 (and confirmed by Adam Ondra in 2011). As of December 2021, female climbers Josune Bereziartu, Ashima Shiraishi, and Kaddi Lehmann have repeated boulder problems at the boulder grade. On 28 July 2023, Katie Lamb became the first female climber to climb an -rated boulder by repeating Box Therapy at Rocky Mountain National Park. However, after Brooke Raboutou repeated the climb In October 2023, the boulder was ultimately downgraded to .
Equipment
Unlike other climbing sports, bouldering can be performed safely and effectively with very little equipment, an aspect which makes the discipline highly appealing, but opinions differ. While bouldering pioneer John Sherman asserted that "The only gear really needed to go bouldering is boulders," others suggest the use of climbing shoes and a chalkbag – a small pouch where ground-up chalk is kept – as the bare minimum, and more experienced boulderers typically bring multiple pairs of climbing shoes, chalk, brushes, crash pads, and a skincare kit.
Climbing shoes have the most direct impact on performance. Besides protecting the climber's feet from rough surfaces, climbing shoes are designed to help the climber secure footholds. Climbing shoes typically fit much tighter than other athletic footwear and often curl the toes downwards to enable precise footwork. They are manufactured in a variety of different styles to perform in different situations. Stiffer shoes excel at securing small edges, whereas softer shoes provide greater sensitivity. The front of the shoe, called the "toe box", can be asymmetric, which performs well on overhanging rocks, or symmetric, which is better suited for vertical problems and slabs.