It will take at least four months to rescue 33 miners trapped underground in Chile, the head of the rescue operation has said.
Rescuers made contact with the miners by lowering a probe into the mine, 17 days after the men became trapped.
The miners, stuck in a mine shaft shelter some 700m (2,300ft) down, sent up a note saying they were all alive.
Rescuers are now preparing to drill a wider hole through which they can bring the miners to the surface.
The chief engineer in charge of the rescue operation, Andres Sougarret, said a larger and more powerful drill would be needed to dig the hole at the San Jose gold and copper mine near the city of Copiapo.
"A shaft 66cm (26 inches) in diameter will take at least 120 days," he said.
Rescuers plan to send narrow plastic tubes down the narrow borehole already drilled with food, hydration gels and equipment that will allow them to communicate with relatives - including cameras and microphones.
'Hope in their eyes'
The men have been trapped since 5 August when the main access tunnel collapsed. They are said to be trapped 4.5 miles (7 km) inside the mine, in a space the size of a small flat.
Before drilling the borehole, rescuers reportedly had to give up efforts to get past the cave-in and to try to reach the miners through a ventilation shaft because of the instability of the mine.
Until Sunday, there had been no word from the miners and hopes for their survival were fading.
The announcement that they were still alive was made on Sunday by Chilean President Sebastian Pinera.
Surrounded by relatives of the miners who have gathered outside the mine, he held up a note from the miners saying: "All 33 of us are fine in the shelter."
"It will take months to get them out," Mr Pinera said. "They'll come out thin and dirty, but whole and strong."
Mr Pinera also saw images of the miners taken by a camera that was lowered down the borehole.
The men were bare-chested, apparently due to the heat, but officials said they were in better condition than expected.
"Many of them approached the camera and put their faces right up against it, like children, and we could see happiness and hope in their eyes," Mr Pinera said.
Celebrations in Santiago
The eldest of the miners, 63-year-old Mario Gomez, sent up a letter to his wife in which he said he was sure the miners would survive.
"Dear Liliana, I'm well, thank God. I hope to get out soon. Have patience and faith," the letter said.
"I haven't stopped thinking about all of you for a single moment."
He also said miners had been able to hear drilling above them as rescuers made several failed attempts to locate them.
The accident has raised concerns about mining safety in Chile, and the company that owns the mine and the national mining service have both been criticised for failing to comply with regulations.
"This company has got to modernise," Mr Gomez said in his letter.
News that the miners were still alive was met with relief across Chile, and people gathered at the main square in the capital, Santiago, to celebrate.
Outside the mine, Mario Gomez's daughter said she could not wait to talk to him.
"No-one will be able to take this happiness away from me," she said.
"I've never felt anything like this in my life. It's like being born again."
The fact that the miners will have a communication channel to relatives is expected to help them cope with the ordeal.
Todd Russell, an Australian miner who was trapped 3,000ft underground in Tasmania after an earthquake in 2006, said he and a second miner who survived the collapse relied on each other for support.
"It's amazing what your body can do," he told the BBC World Service. "We survived on hope and courage, and each other, [and] we were lucky enough to have a bit of underground mine water."
"They're lucky that they've got 33 guys there with them that they can rely on each other," Mr Russell said.