Mount Everest is the highest mountain on Earth, as measured by the height of its summit above sea level, which is 8,848 meters or 29,028 feet. The mountain, which is part of the Himalaya range in High Asia, is located on the border between Nepal and Tibet, China. By the end of the 2007 climbing season there had been 3,679 ascents to the summit by 2,436 individuals. There have been 210 deaths on the mountain, where conditions are so difficult that most corpses have been left where they fell; some are visible from standard climbing routes.

Climbers range from experienced mountaineers to relative novices who count on their paid guides to get them to the top. This means climbers are a significant source of tourist revenue for Nepal, whose government also requires all prospective climbers to obtain an expensive permit, costing up to $25,000 (USD) per person.

Mt. Everest has two main climbing routes, the southeast ridge from Nepal and the northeast ridge from Tibet, as well as many other less frequently climbed routes.[21] Of the two main routes, the southeast ridge is technically easier and is the more frequently-used route. It was the route used by Edmund Hillary and Tenzing Norgay in 1953 and the first recognised of fifteen routes to the top by 1996. This was, however, a route decision dictated more by politics than by design as the Chinese border was closed to foreigners in 1949. Reinhold Messner (Italy) reached the summit of the mountain solo for the first time, without supplementary oxygen or support, on the more difficult Northwest route via the North Col to the North Face and the Great Couloir, on August 20 1980. He climbed for three days entirely alone from his base camp at 6500 meters. This route has been noted as the 8th climbing route to the summit.

Most attempts are made during May before the summer monsoon season. A change in the jet stream at this time of year reduces the average wind speeds high on the mountain. While attempts are sometimes made after the monsoons in September and October, the additional snow deposited by the monsoons and the less stable weather patterns makes climbing more difficult.

Southeast ridge

The ascent via the southeast ridge begins with a trek to Base Camp at 5,380 m (17,600 ft) on the south side of Everest in Nepal. Expeditions usually fly into Lukla (2,860 m) from Kathmandu and pass through Namche Bazaar. Climbers then hike to Base Camp, which usually takes six to eight days, allowing for proper altitude acclimatization in order to prevent altitude sickness. Climbing equipment and supplies are carried by yaks, dzopkyos (yak hybrids) and human porters to Base Camp on the Khumbu Glacier. When Hillary and Tenzing climbed Everest in 1953, they started from Kathmandu Valley, as there were no roads further east at that time.

Climbers will spend a couple of weeks in Base Camp, acclimatizing to the altitude. During that time, Sherpas and some expedition climbers will set up ropes and ladders in the treacherous Khumbu Icefall. Seracs, crevasses and shifting blocks of ice make the icefall one of the most dangerous sections of the route. Many climbers and Sherpas have been killed in this section. To reduce the hazard, climbers will usually begin their ascent well before dawn when the freezing temperatures glue ice blocks in place. Above the icefall is Camp I at 6,065 m (19,900 ft).

From Camp I, climbers make their way up the Western Cwm to the base of the Lhotse face, where Camp II or Advanced Base Camp (ABC) is established at 6,500 m (21,300 ft). The Western Cwm is a relatively flat, gently rising glacial valley, marked by huge lateral crevasses in the centre which prevent direct access to the upper reaches of the Cwm. Climbers are forced to cross on the far right near the base of Nuptse to a small passageway known as the "Nuptse corner". The Western Cwm is also called the "Valley of Silence" as the topography of the area generally cuts off wind from the climbing route. The high altitude and a clear, windless day can make the Western Cwm unbearably hot for climbers.

From ABC, climbers ascend the Lhotse face on fixed ropes up to Camp III, located on a small ledge at 7,470 m (24,500 ft). From there, it is another 500 metres to Camp IV on the South Col at 7,920 m (26,000 ft). From Camp III to Camp IV, climbers are faced with two additional challenges: The Geneva Spur and The Yellow Band. The Geneva Spur is an anvil shaped rib of black rock named by a 1952 Swiss expedition. Fixed ropes assist climbers in scrambling over this snow covered rock band. The Yellow Band is a section of interlayered marble, phyllite, and semischist which also requires about 100 metres of rope for traversing it.

On the South Col, climbers enter the death zone. Climbers typically only have a maximum of two or three days they can endure at this altitude for making summit bids. Clear weather and low winds are critical factors in deciding whether to make a summit attempt. If weather does not cooperate within these short few days, climbers are forced to descend, many all the way back down to Base Camp.

A view of Everest southeast ridge base camp. The Khumbu Icefall can be seen in the left. In the center are the remains of a helicopter that crashed in 2003.
From Camp IV, climbers will begin their summit push around midnight with hopes of reaching the summit (still another 1,000 metres above) within 10 to 12 hours. Climbers will first reach "The Balcony" at 8,400 m (27,700 ft), a small platform where they can rest and gaze at peaks to the south and east in the early dawn light. Continuing up the ridge, climbers are then faced with a series of imposing rock steps which usually forces them to the east into waist deep snow, a serious avalanche hazard. At 8,750 m (28,700 ft), a small table-sized dome of ice and snow marks the South Summit.

From the South Summit, climbers follow the knife-edge southeast ridge along what is known as the "Cornice traverse" where snow clings to intermittent rock. This is the most exposed section of the climb as a misstep to the left would send one 2,400 m (8,000 ft) down the southwest face while to the immediate right is the 3,050 m (10,000 ft) Kangshung face. At the end of this traverse is an imposing 12 m (40 ft) rock wall called the "Hillary Step" at 8,760 m (28,750 ft).

Hillary and Tenzing were the first climbers to ascend this step and they did it with primitive ice climbing equipment and without fixed ropes. Nowadays, climbers will ascend this step using fixed ropes previously set up by Sherpas. Once above the step, it is a comparatively easy climb to the top on moderately angled snow slopes - though the exposure on the ridge is extreme especially while traversing very large cornices of snow. With increasing numbers of people climbing the mountain in recent years, the Step has frequently become a bottleneck, with climbers forced to wait significant amounts of time for their turn on the ropes, leading to problems in getting climbers efficiently up and down the mountain. After the Hillary Step, climbers also must traverse a very loose and rocky section that has a very large entanglement of fixed ropes that can be troublesome in bad weather. Climbers will typically spend less than a half-hour on "top of the world" as they realize the need to descend to Camp IV before darkness sets in, afternoon weather becomes a serious problem, or supplemental oxygen tanks run out.

Northeast ridge

Everest North Face, Tibet
The northeast ridge route begins from the north side of Everest in Tibet. Expeditions trek to the Rongbuk Glacier, setting up Base Camp at 5,180 m (17,000 ft) on a gravel plain just below the glacier. To reach Camp II, climbers ascend the medial moraine of the east Rongbuk Glacier up to the base of Changtse at around 6,100 m (20,000 ft). Camp III (ABC - Advanced Base Camp) is situated below the North Col at 6,500 m (21,300 ft). To reach Camp IV on the north col, climbers ascend the glacier to the foot of the col where fixed ropes are used to reach the North Col at 7,010 m (23,000 ft). From the North Col, climbers ascend the rocky north ridge to set up Camp V at around 7,775 m (25,500 ft). The route goes up the north face through a series of gullies and steepens into downsloping slabby terrain before reaching the site of Camp VI at 8,230 m (27,000 ft). From Camp VI, climbers will make their final summit push. Climbers must first make their way through three rock bands known as First Step: 27,890 feet - 28,000 feet, Second Step: 28,140 feet - 28,300 feet, and Third Step: 28,510 feet - 28,870 feet. (The Second Step includes a climbing aid called the "Chinese ladder", a metal ladder placed semi-permanently in 1975 by a party of Chinese climbers. It has been almost continuously in place since, and is used by virtually all climbers on the route.) Once above these steps, the final summit slopes (50 to 60 degrees) to the top.

China is paving a 130-km (66-mile) dirt road from Tingri County to its Base Camp in order to accommodate growing numbers of climbers on their side of the mountain. It will become the highest asphalt-paved road in the world. Construction began on June 18, 2007, at a cost of 150 million yuan (US$19.7 million). China also plans on routing the 2008 Olympic Torch Relay over Everest, going up the South Col route and back down the North Col route, on the way to the 2008 Summer Olympics in Beijing.

History

Early expeditions
In 1885, Clinton Thomas Dent, president of the Alpine Club, suggests that climbing Mount Everest is possible in his book Above the Snow Line.

On June 8, 1924, George Mallory and Andrew Irvine, both of the United Kingdom, made an attempt on the summit via the north col/north ridge route from which they never returned.

On May 1, 1999, the Mallory and Irvine Research Expedition found Mallory's body in the predicted search area near the old Chinese camp. Controversy has raged in the mountaineering community as to whether or not one or both of them reached the summit 29 years before the confirmed ascent (and of course, safe descent) of Everest by Sir Edmund Hillary and Tenzing Norgay in 1953. The general consensus among climbers has been that they did not.

Mallory had gone on a speaking tour of the United States the year before in 1923; it was then that he exasperatedly gave the famous reply, "Because it is there," to a New York journalist in response to hearing the question, "Why climb Everest?" for seemingly the thousandth time.

In 1933, Lady Houston, a British millionaire ex-showgirl, funded the Houston Everest Flight of 1933, which saw a formation of aircraft led by the Marquess of Clydesdale fly over the summit in an effort to deploy the British Union Flag at the top.

Early expeditions – such as Bruce's in the 1920s and Hugh Ruttledge's two unsuccessful attempts in 1933 and 1936 – tried to make an ascent of the mountain from Tibet, via the north face. Access was closed from the north to western expeditions in 1950, after the Chinese reasserted control over Tibet. However, in 1950, Bill Tilman and a small party which included Charles Houston, Oscar Houston and Betsy Cowles undertook an exploratory expedition to Everest through Nepal along the route which has now become the standard approach to Everest from the south.

First successful ascent by Tenzing and Hillary
In 1953, a ninth British expedition, led by John Hunt, returned to Nepal. Hunt selected two climbing pairs to attempt to reach the summit. The first pair (Tom Bourdillon and Charles Evans) came within 100 m (300 feet) of the summit on 26 May, but turned back after becoming exhausted. Two days later, the expedition made its second and final assault on the summit with its second climbing pair, the New Zealander Edmund Hillary and Sherpa Tenzing Norgay from Nepal. They reached the summit at 11:30 a.m. local time on May 29, 1953 via the South Col Route. At the time, both acknowledged it as a team effort by the whole expedition, but Tenzing revealed a few years later that Hillary had put his foot on the summit first. They paused at the summit to take photographs and buried a few sweets and a small cross in the snow before descending.

News of the expedition's success reached London on the morning of Queen Elizabeth II's coronation. Returning to Kathmandu a few days later, Hunt (a Briton) and Hillary (a subject of Elizabeth, through her role as head of state of New Zealand) discovered that they had been promptly knighted in the Order of the British Empire, a KBE, for the ascent. Tenzing (a subject of the King of Nepal) was granted the George Medal by the UK. Hunt was ultimately made a life peer in Britain, while Hillary became a founding member of the Order of New Zealand.

1996 disaster
Main article: 1996 Everest Disaster.
During the 1996 climbing season, fifteen people died trying to come down from the summit, making it the deadliest single year in Everest history. Eight of them died on May 11 alone. The disaster gained wide publicity and raised questions about the commercialization of Everest.

Journalist Jon Krakauer, on assignment from Outside magazine, was in one of the affected parties, and afterwards published the bestseller Into Thin Air which related his experience. Anatoli Boukreev, a guide who felt impugned by Krakauer's book, co-authored a rebuttal book called The Climb. The dispute sparked a large debate within the climbing community. In May 2004, Kent Moore, a physicist, and John L. Semple, a surgeon, both researchers from the University of Toronto, told New Scientist magazine that an analysis of weather conditions on May 11 suggested that freak weather caused oxygen levels to plunge approximately 14%.[25][26]

The storm's impact on climbers on the mountain's other side, the North Ridge, where several climbers also died, was detailed in a first hand account by British filmmaker and writer Matt Dickinson in his book The Other Side of Everest.

2003 - 50th Anniversary of First Ascent
2003 marked the 50th anniversary of the first ascent, and a record number of teams, including some very distinguished climbers, climbed or attempted to climb the mountain

2006 - North Face ski descent
On 16 May 2006, adventurers Tormod Granheim and Tomas Olsson skied the Norton Couloir from the summit to the North Col. During the descent Olsson fell an estimated 1700 meters to his death.

2006 - David Sharp controversy
Double-amputee climber Mark Inglis revealed in an interview with the press on May 23, 2006, that his climbing party, and many others, had passed a distressed climber, David Sharp, on May 15, sheltering under a rock overhang 450 meters below the summit, without attempting a rescue. The revelation sparked wide debate on climbing ethics, especially as applied to Everest. The climbers who left him said that the rescue efforts would be useless and only cause more deaths because of how many people it would have taken to pull him off.

Much of this controversy was captured by the Discovery Channel while filming the television program Everest: Beyond the Limit. A crucial decision affecting the fate of Sharp is shown in the program, where an early returning climber (Max Chaya) is descending and radios to his base camp manager (Russell Brice) that he has found a climber in distress. He is unable to identify Sharp, and Sharp had chosen to climb solo without any support, so he did not identify himself to other climbers. The base camp manager assumes that Sharp is part of a group that has abandoned him, and informs his climber that there is no chance of him being able to help Sharp [at 8000+ meters in altitude, barely anyone has the strength to help another man who is only semi conscious, and Max Chaya is only an amateur mountaineer]. As Sharp's condition deteriorates through the day and other descending climbers pass him, his opportunities for rescue diminish: his legs and feet curl from frost-bite, preventing him from walking; the later descending climbers are lower on oxygen and lack the strength to offer aid; time runs out for any Sherpas to return and rescue him. Most importantly, Sharp's decision to forgo all support leaves him with no margin for recovery.

As this debate raged, on May 26, Australian climber Lincoln Hall was found alive, after being declared dead the day before. He was found by a party of four climbers (Dan Mazur, Andrew Brash, Myles Osborne and Jangbu Sherpa) who, giving up their own summit attempt, stayed with Hall and descended with him and a party of 11 Sherpas sent up to carry him down. Hall later fully recovered. Similar actions have been recorded since, including on May 21, 2007, when Canadian climber Meagan McGrath initiated the successful high-altitude rescue of Nepali Usha Bista.