In 2019, 11 climbers died on the breathtaking Mount Everest. It was the deadliest year at the world's highest peak's since 2015, and the fourth deadliest on record. Here are pictures from an especially treacherous climbing season at the landmark that borders China and Nepal. 

British climber Robin Fisher, seen here at left with his partner, Kristyn Carriere, in an April 19 Everest selfie, died May 25 after reaching the 29,029-foot summit. Altitude sickness was blamed.

A few days prior to his death, Fisher wrote on Instagram that he hoped to wait out the throngs of climbers scaling the mountain's south side.

In 2019, a record 855 people reached Everest's summit in May, the month that historically comprises climbing season. The congestion slowed ascents, and prolonged climbers' time in the low-oxygen "death zone" above 26,000 feet. This long line is captured mid-trek on May 22.

Like most climbers, Nick Hollis, seen in a 2019 Everest selfie, reached the summit via the south side. The British man told Reuters there weren't too many climbers, just too many "incompetent climbers."  

On the way up Everest, Hollis told Reuters, "It's no exaggeration to say you are walking over [frozen] bodies." He reached the summit on May 21. 

Ameesha Chauhan recuperates at a hospital in Kathmandu, the capital of Nepal, on May 27. The Everest climber from India was delayed in her descent by the crowds. 

Ameesha Chauhan, the hospitalized climber, suffered frostbite during her Everest journey. 

This picture from 2018's climbing season shows climbers waiting to see a doctor at the Everest Base Camp Medical Clinic. The pop-up facility, which is open from April to the end of climbing season in May, was established in 2003.

Since the first Everest expedition in 1922, some 300 people have died on the mountain. In 2019, in addition to the 11 noted fatalities, the bodies of four unidentified victims from presumed climbs past were found. Workers in Nepal are seen unloading one of the corpses on May 23 at a hospital helipad in Kathmandu.

The four unidentified bodies were found as the Nepalese government spent 45 days purging Everest of more then 24,000 pounds of trash. Here, members of the army toss bags bound for recycling on May 27 in the town of Namche Bazar.

A gin bottle is among the artifacts in a discard pile recovered from the mountain in the 2019 clean-up effort.

These empty oxygen tanks were also collected by the Everest clean-up crew. While the rare adventurer attempts Everest without the aid of extra oxygen, most rely on supplemental canisters of the element starting at about the 23,000-foot elevation mark. 

An Arizona doctor complained to the New York Times about 2019's unruly, zoo-like atmosphere on Everest. This litter-strewn May 2018 shot of Camp 4 shows how climbers have been leaving a mark on the mountain for years. 

Climbers scale the south side of Everest on May 22. Nepal officials said any changes to permitting or access would have to wait until after they concluded their findings on this season's deaths.  

Even as Everest deaths mounted, climbers kept climbing. Here, two are seen along a path in the mountain region on May 27. 

Here's another view of climbers along an Everest path on May 27. 

Veteran Everest sherpa Pemba Dorje made it to the summit with his wife,  Kanchhi Maya Tamang, two days after this May 20 photo was captured at Camp 3, at about the 24,500-foot elevation mark. 

Not all 2019 Everest climbers were adventure-seekers. A team of Nepali government workers, seen here doing an equipment check on April 8 in Kathmandu, set out to reach the summit in order to measure whether the region's 2015 7.8-magnitude earthquake lowered the peak's elevation.

Two widows of sherpas who died on the mountain in 2013 and 2014, respectively, are seen training for their own climb. The women, Nima Doma, right, and Furdiki Sherpa, left, reached the summit on May 23.

This stunning aerial shot of Everest was taken on April 27.

More Everest climbers hail from India than any other country. Here, a memorial service for the 2019 Everest victims is held on May 29 in Kolkata, India. 

May 29 is known as Everest Day, an occasion that marks the first-ever Everest summit as accomplished by Edmund Hillary, a New Zealand mountaineer, and Tenzig Norgay, the sherpa, or mountain guide, on May 29, 1953. Here, Hillary's daughter, Sarah Hillary, and a Nepalese official decorate statues of the two pioneers at the 2019 ceremony in Kathmandu.

Travelers board an airplane on May 27 at Tenzing-Hillary Airport in Lukla, Nepal. The airport, named for Edmund Hillary, who supervised its construction, and Tenzig Norgay, is the gateway to Everest. It's known as the most dangerous airport in the world. 

Even before Everest's deadly climbing season began, three people were killed on April 14 when a Let L-410 Turbolet twin-engine plane collided on takeoff with two helicopters at Tenzing-Hillary airport, where the runway is short and the terrain is challenging.

The body of a victim of the April 14 Tenzing-Hillary crash is carried out of a helicopter at Tribhuvan University Teaching Hospital in Kathmandu.

A 2019 Everest success story belongs to Saray Khumalo, who looks at a picture of her May 23 summit. Khumalo, a business exec from South Africa, is the first black African woman to conquer Everest. 

Purnima Shrestha, a photojournalist from Nepal who reached Everest's summit in 2018, gets a tattoo commemorating the achievement on 2019's Everest Day in Kathmandu. 

The 2019 season didn't claim victims just on Everest. In the Indian state of West Bengal on May 29, mourners pay tribute to Dipankar Ghosh, a 52-year-old Indian photographer, who died as he descended the world's fifth-highest peak, Mount Makalu, located about 12 miles southeast of Everest.

The last time more than 10 people died on Everest was 2015, when the 7.8-magnitude earthquake triggered an avalanche that killed at least 18. Sherpas are seen here awaiting a rescue helicopter during that exceptionally deadly season. 

On April 26, 2015, rescuers carry an avalanche victim at Everest Base Camp. Some 9,000 people throughout Nepal died in the massive quake.  

A sherpa who was caught in the 2015 Everest Base Camp avalanche is tended to on the day of the disaster-triggering quake. 

A 2014 avalanche killed 16 sherpas as they trekked through Everest's Khumbu Icefall area. Here, a survivor of the disaster, Dawa Tashi, lies at Kathmandu's Grande International Hospital on April 18, 2014. 

A helicopter heads toward Everest Base Camp in April 2018. 

When this shot of person being rendered aid was captured at Everest Base Camp in 2018, the big concern was that costly — and sometimes unnecessary — helicopter rescues were being pushed on climbers.

The bodies of Indian climbers who died on Everest in 2016 remained on the mountain as bad weather prevented rescuers from retrieving them. Here, the remains finally arrive in Kathmandu a year later, in May 2017.  

In 2018, four climbers died on Everest, including Japan's Nobukazu Kuriki, who'd lost parts of nine of his fingers to frostbite during an aborted 2012 Everest attempt. Kuriki's body is seen outside the morgue at Tribhuvan University Teaching Hospital in May 2018. 

In a famous 1996 Everest disaster immortalized in two movies, Into Thin Air and Everest, eight people died when a blizzard struck during their group's descent. American Dr. Seaborn Beck Weathers, seen arriving back home in Texas in May 1996, survived, albeit with injuries that forced the partial amputation his right arm, the removal of the fingers on his left hand and the reconstruction of his nose.

The toll of Everest is seen in the face of Australian climber Robert Gropel as he sits in a Kathmandu hotel on May 24, 2016, two days after his wife, Dr. Maria Strydom, died from altitude sickness as they neared the summit. Strydom's death was one of seven on Everest that year.