Showman David Blaine has left hospital after spending seven days under water.
The week-long stunt caused liver damage, pins and needles in his feet and hands, some loss of sensation and rashes, Blaine's doctor said.
Dr Murat Gunel said there was evidence of liver failure on the second day. "I told him he needed to get out of the water, and he refused me," he said.
"He said he did not want to let the people down." Blaine failed to break the world record for holding breath.
The illusionist received food and air through tubes during the seven days he spent in a water-filled sphere in New York.
At the end of the ordeal, he tried to break the nine-minute record for holding breath but divers pulled him out after seven minutes when he began struggling.
Blaine managed to hold his breath underwater for seven minutes
Crowds of spectators and millions of TV viewers saw him rescued.
Appearing shaken and weak, he thanked his supporters and left for hospital.
"This was a very difficult week but you all made it fly by with your strong spirit, your energy. Thank you so much everybody," Blaine told a cheering crowd in Lincoln Square.
He appeared to have freed himself from chains attached to his hands but was struggling to free his feet when the divers entered the tank and pulled him out.
Blaine received medical treatment over the weekend while in the tank because his peeling skin and overall condition were worrying doctors.
"They're worried about loss of dexterity," his spokesman Pat Smith said. "There is considerable concern about both his hands and his muscle tone."
In order to receive medical attention, Blaine stuck his hand out of a hole at the top of a tank, allowing doctors to remove specially created gloves, apply lotion and put on new gloves.
Before embarking on the stunt, the 33-year-old US showman shed 50lbs (23kg) in body weight to improve the efficiency of the way his body uses oxygen.
Blaine's peeling skin and overall condition were worrying doctors
Prolonged submersion in water poses a number of hazards, including nerve damage, blackouts, sleep deprivation and skin problems.
Blaine had said his skin was causing him pain "like constant pins and needles" after five days in the acrylic sphere.
A lack of adequate oxygen, especially after seven days underwater, also carries a risk of irreversible brain injury, according to medical experts.
Blaine's previous stunts have included spending 61 hours inside a block of ice and fasting for 44 days in a Perspex box over London's River Thames.