29,029.

That's how many feet in the air the peak of Mount Everest towers over Nepal, and the world, in its gleaming white brilliance. Since the British first billed it as the highest point on Earth in 1856, that snow-capped tip, where almost no life can survive without mechanical assistance due to oxygen levels that are one-third those at sea level, sings a Siren's song to some high achievers. In 1953, Sir Edmund Hillary and Tenzing Norgay Sherpa offered photographic evidence that proved the feat achievable. Achievable, yes, but maddeningly difficult. The quest to reach (and return from) it has cost humanity more than 250 lives over the years. It's such a herculean task that it's become the linguistic stand-in for any difficult job - writing that novel or completing that marathon was "my own personal Everest," some might say.

For Maria Strydom and her husband Robert Gropel, climbing Everest while adhering to a strict vegan diet was their "own personal Everest."

The 34-year-old Strydom, a lecturer at Monash Business School in Melbourne, had a message she wanted to share with the world: Veganism is not a handicap.

She and her husband Robert Gropel, a Melbourne veterinarian with Ivanhoe East Veterinary Hospital, both stuck closely to the rigorous diet required by vegans - no animal products whatsoever, which extends from scrambled eggs to most chocolate chip cookies - for which they experienced criticism. Some believed they didn't receive enough iron and protein in their diet for such strenuous physical activity.

"It seems that people have this warped idea of vegans being malnourished and weak," Strydom said in an interview on Monash's blog. "By climbing the seven summits we want to prove that vegans can do anything and more."

Those "seven summits," refer to the highest peak on each of the seven continents. They would have to wait on Everest, though.

The mountain has been mostly untouched by ambitious adventurers for the past two years - in fact, last year was the first to pass without a climber reaching the summit - due to a pair of natural disasters. The first tragedy swept through in 2014 in the form of an avalanche, the mountain's deadliest accident to date, which immediately killed 12 Sherpa guides and injured three more. The second arrived in 2015 as a pair of earthquakes that claimed more than 8,000 lives in Nepal, CNN reported.

That gave the couple time to train vigorously in preparation. In that intervening years, they certainly proved that their diet wouldn't keep them from mountain-climbing by scaling Denali in Alaska, Mount Ararat in Turkey and Kilimanjaro in Africa, among others.

But Everest is Everest, and they wanted to tackle it, even given the spate of recent deaths, even when Gropel's uncle warned them not to.

"I had a foreboding, a bad feeling," Kurt Gropel told the Sydney Morning Herald. "I said, 'I don't want you to go' - they weren't very happy about that."

"Everest is a killer," Kurt said. "There are 200 corpses up there that decorate the path. They are all people who thought they could go up and down."

But the couple felt prepared.

"A very experienced guide in Alaska once told us that of all the things you can regret once you are on the mountain, you will never regret over-training," Strydom said before the climb. "It is also important to get experience spending long periods on a mountain."

Everest, though, proved unscalable for them. The couple reached Camp Four, the final camp 400 meters from the summit before both suffered from high-altitude pulmonary edema, colloquially known as altitude sickness. It caused fluid to build up in Strydom's brain, which killed her on Saturday. Gropel, alive but fighting a fluid build-up in his lungs, had to be taken down the mountain by sled, The Sydney Morning Herald reported. He was taken to a hospital in Kathmandu, Nepal.

Heinz Gropel, Robert's father, told the Australian Robert will likely recover, at least in body.

"Physically he's OK, we think," Heinz said. "Mentally he is a mess. He's just lost his wife. These guys were not amateurs, they were experienced climbers."

Strydom was one of three people seemingly in the primes of their respective lives - one has to be to scale Everest - to have succumbed the mountain's many dangers since Thursday.

The latest, according to the Associated Press: Subash Paul, an Indian climber who had fallen sick and was being helped down the mountain by Sherpa guides when he died overnight. "It is not clear what happened," expedition organizer Wanchu Sherpa, of Trekking Camp Nepal, told CNN. "We believe the weather suddenly deteriorated at some point, and the team lost direction."

Two other members of Paul's team, Paresh Nath and Goutam Ghosh, are now missing, CNN reported. "We are trying to communicate with other expedition teams around that level to locate the missing climbers," Gyanendra Shrestha of the Nepal Tourism Department told CNN.

Meanwhile, around 30 more climbers have become sick, frostbitten or both near the summit during the past few days, the AP reported.

Another member of Strydom and Gropel's climbing party, 36-year-old Eric Arnold, also died.

For him, the quest was one instilled since childhood. The professional mountaineer and motivational speaker, who The Washington Post's Annie Gowen profiled before he attempted his climb, had tried in three previous years to scale the mountain. It was his life's passion. As he told The Post, "Mount Everest is my big childhood dream." Hanging over his teenage bed were two posters: one of actress and model Pamela Anderson and one less seen in young men's bedrooms, one of the mountain he planned to someday climb.

After four years of attempts, Arnold finally reached the summit, and even managed to send a tweet from it, but he began suffering from altitude sickness during his descent, the Associated Press reported.

Though he had with him enough oxygen, Arnold grew too weak to make it to the lower altitude required for his symptoms to begin subsiding. He died on Friday evening.

Before his fatal attempt, his fourth in all, Arnold told The Post that he didn't feel as if he had a choice, even knowing the risks.

"A lot of people say, 'Maybe it's not your turn, maybe it's not your fate, maybe the mountain is telling you not to climb it,'" he said. "But I still have a passion for it. When I realized that, I decided I have to go back."

The fourth person who has died during this year's climbing season was simply doing his job.

Twenty-five-year-old Phurba Sherpa plunged to his death on Thursday while attempting to fix a route for future climbers 150 meters under the summit, CNN reported. Though deaths of the men and women who attempt to scale the mountain each year often make headlines, those of the Nepalese Sherpas who both guide climbers and perform maintenance along the route rarely do.

The Sherpas have worked on the mountain for so long that National Geographic reported, "'sherpa' with a small 's' has come to signify anyone who carries loads." These are the people who set up Base Camp, install and fix ropes throughout the path to the summit and guide paying climbers to the top. The work pays extraordinarily well, anywhere from $4,000 to $30,000 a season in a country with an annual per capita income of $700.

But it's dangerous work, and Phurba Sherpa is far from the first to perish while performing it. Outside reported the annual fatality rate for Everest Sherpas from 2004 to 2014 to be 4,053 per 100,000 (as compared to miners (25:100,000) or commercial fishermen (124:100,000)). That number is admittedly skewed, as there aren't many performing the work and the 2014 avalanches caused that number to spike (it was 1,332: 100,000 from 2000 to 2010). Still, the result is striking and shows again how dangerous the mountain can be, even for those who know it best.

On Everest, death is not necessarily a sign of failure so much as one of a particularly sad inevitability. Much like many places humans have ventured in our boundless curiosity - from the ocean depths to outer space - it cannot sustain life, and it often takes them. Gyanendra Shrestha, a Nepalese official at Everest Base Camp, told the BBC that altitude sickness and fatigue, alongside natural factors like blizzards and avalanches, kill a few climbers each year. It's a potential outcome known to its climbers and gruesomely illustrated along the way by the almost 200 bodies that have frozen on or near the peak.

The most unavoidable for those reaching the top is what is believed to be the body of Tsewang Paljor, a young Indian climber who died in the 1996 blizzard, Outside reported. To reach the summit on the north side of the mountain, climbers sometimes have to step over his frozen legs, which are capped by the green shoes that have earned the body the nickname "Green Boots."

That isn't to say it's unconquerable. Far from it: More than 4,000 people have reached the summit since 1953. This year alone, more than 330 have reached it, according to NBC. But, as the body count continues to rise with each passing year, some familiar with the mountain are beginning to argue that mounting it isn't worth the risks.

"I used to see the media stories that came out and they'd be only about death and destruction, and I'd say, 'Well, my mountain is not about death,'" Dave Hahn, an RMI Expedition mountain guide who has summited Everest 15 times, told BBC last year. "But the last two years have brought such a huge loss of life that it's become hard for me to continue to make that argument."