British adventurer Henry Worsley died while trying to make history by crossing the Antarctic alone in a trip backed by members of the royal family, his wife said.
Worsley, 55, was just 30 miles (48 kilometers) from the finish when he called for help and was airlifted to a hospital in Chile on Friday suffering from exhaustion and severe dehydration.
"It is with heartbroken sadness I let you know that my husband, Henry Worsley, has died following complete organ failure," his wife Joanna said in a statement.
Worsley died in the Clinica Magallanes in Punta Arenas, Chile, "despite all efforts" of medical staff, she added.
The clinic said in a statement he was admitted on Saturday morning and died early Sunday afternoon. It did not yet say when his body might be returned.
In his final statement from the expedition, Worsley expressed his dismay at having to pull out so close to the end after covering almost 1,500 kilometers on foot, dragging his equipment in a sledge.
"My journey is at an end. I have run out of time, physical endurance and a simple sheer inability to slide one ski in front of the other," he said in an audio message, sounding exhausted but not fear-stricken.
"Many mountaineers battle away and fail to reach the summit. My summit is just out of reach."
His wife said Worsley had raised £100,000 ($143,000, 132,000 euros) for the Endeavour Fund, a charity to help wounded military veterans and backed by Prince William, his wife Kate and brother Prince Harry.
William paid tribute to Worsley and his attempt to cross Antarctica via the South Pole.
"Harry and I are very sad to hear of the loss of Henry Worsley. He was a man who showed great courage and determination and we are incredibly proud to be associated with him," William said.
Modern-day explorer hero
A former Army officer and father of two from London, Worsley had hoped to become the first man to cross the Antarctic solo, unsupported and without assistance.
The feat was left unfinished a century ago by explorer Ernest Shackleton, whom Worsley described as his "hero."
Worsley was 71 days into the attempt when he called for help. A statement on his website said he was found to be suffering from peritonitis, an inflammation of the lining of the abdomen.
Another British explorer, Ranulph Fiennes, dropped out of a similar charity trek in 2013.
Worsley spent 36 years in the British army, and had a keen interest in the lives of Edwardian explorers.
He authored a book about Shackleton, who died of a heart attack on his way back to Antarctica for a new expedition in 1922.
Shackleton's granddaughter Alexandra Shackleton sent her condolences.
"This is a day of great sadness. Henry will be a huge loss to the adventuring world," she told the BBC.
"The fact that he very, very nearly made it - only 30 miles short of his goal - makes it in some way seem worse."
Tributes poured in for Worsley, including from retired football star David Beckham.
He recounted a story about the explorer lending him his Union Jack flag for a snapshot when the former England captain made his own Antarctic trip.
"No words can describe the sadness of the loss of Henry Worsley," Beckham wrote on his Facebook page.
Paul Rose, a former base commander for the British Antarctic Survey, told the BBC Worsley's expedition was "unheard of."
"The conditions haven't changed from (legendary explorer Robert Falcon) Scott and Shackleton's days. The Antarctic is still an incredibly hostile place."