How 43 people died on the world's highest trekking pass
Adventure turned to tragedy for a young Australian couple on Saturday, after coming within touching distance of their life goal, the summit of Mount Everest. 
Monash University lecturer Maria Strydom, 34, and her husband, Melbourne vet Robert Gropel, began their ascent to the top of the world's highest mountain more than a month ago. 
On Saturday, Dr Strydom's body was being transported down thousands of metres of brutal terrain after severe altitude sickness caused fluid to swell in her brain, while her husband continues to battle against congestive heart failure.  
The couple had successfully reached Camp Four, 400 metres below the summit by Friday, satellite pings posted online from their phones reveal.
With a cyclone on the horizon and the summit in reach, Dr Strydom willed herself to the edge of her body's capacity. A post online from Dr Gropel's veterinary practice reveals the group had set out under the cover of darkness. 
"They will set out approximately 10pm local time and will have to contend with darkness, lack of oxygen, the infamous Hillary step and a race against time," the hospital stated. 
Furtengi Sherpa, the Operational Manager of Seven Summit Treks, said that Dr Strydom had been battling illness as the final push began. 
"She was tired and energy was down, there was enough oxygen to supply for her to give energy continuing back around altitude of 7800 metres," he said. 
The expedition had already lost another climber by the time the elements had taken hold of Dr Strydom. Dutch man Eric Arnold had told teammates "my body has no energy left," before dying in his sleep, according to Dutch news agency ANP.
Suffering from altitude sickness and just hundreds of metres from the summit, the Melbourne lecturer was forced to turn back through the "death zone," where oxygen-starved climbers battle against frostbite, low-atmospheric pressures, fierce winds and bodies litter the climbing trail. 
"She could not resist anymore here weakness and she stopped breathing right there," said Furtengi. 
Upon hearing of Mr Arnold's death on Saturday, Dr Strydom's mother Maritha, desperately tried to get in touch with the expedition using "all possible ways to call locate them." 
By Sunday morning the news she dreaded had found its way home. 
"My beautiful girl," she wrote on Facebook. "I'm just [too] devastated to communicate." 
Dr Strydom's distraught sister, Aletta Newman, lashed out at Arnold Coster Expeditions, the partner climbing company responsible for the summit attempt. 
"I have just read online that my sister Maria died on Everest," Ms Newman wrote on Facebook. "Why can't you contact the family before we have to find out this way? Please contact the family so we can get facts!". 
Dr Gropel's father Heinz said that he and his wife Pat were preparing to fly overseas if necessary to be with their son. 
"They had to take him down by sled. He suffered high altitude pulmonary oedema, they'll chopper him down to Kathmandu and probably fly him either to Singapore or to Melbourne," Mr Gropel said. 
"[Last night, Maria's] mother rang and said she's died. And our son is still up there at Camp Two on the Khumbu glacier in north-eastern Nepal." 
According to Mr Gropel, Dr Gropel is the only vet at the Ivanhoe East Veterinary Hospital, in Melbourne's north-east. 

 While the Department of Foreign Affairs endeavours to get the couple home, tributes have begun to flow for the 34-year-old expert in banking and finance. 
"The Monash University community is deeply saddened by the tragic news of the loss of Dr Strydom on Mount Everest," the Melbourne university said in a statement. 
Students also mourned the loss of the young academic. "A wonderful human being and highly intelligent," wrote former Monash student, Apurv Maru. 
"Goodbye warrior princess," wrote fellow climber Juan Sarjanovich. 
Dr Strydom and her husband Dr Gropel were passionate vegan campaigners and wanted to tackle Everest to challenge the diet's stereotypes. 
"It seems that people have this warped idea of vegans being malnourished and weak," Dr Strydom said in   March. "By climbing the seven summits we want to prove that vegans can do anything and more."
Over the past eight years, the experienced mountaineers had successfully climbed Denali in Alaska, Aconcagua in Argentina, Mount Ararat in eastern Turkey, and Kilimanjaro in Africa. 
Dr Strydom's death was the third climbing related fatality in the Himalayas this week. On Thursday, a 25-year-old Nepali sherpa plunged more than two kilometres to his death. The sherpa, who has not been identified, slipped while he was fixing ropes on nearby Lhotse, the world's fourth highest peak.
The deaths are likely to hit Nepal's mountaineering community which is still recovering from the past two disaster-stricken climbing seasons. The country's devastating earthquake last year caused an avalanche that killed 22 people at base camp. In 2014, an avalanche above base camp killed 16 Sherpa guides.
- With Carolyn Webb