Kirk Jones, the only person to survive a plunge over Niagara Falls without any protection devices, has claimed it was a spur of the moment act.
Relatives say Jones had been planning his leap for some time
"It was an impulsive one-second thing and in a second-and-a-half I was in the water," Mr Jones, 40, told a Detroit television station.
But family and friends of the Michigan daredevil say Mr Jones had been planning the dive for months and had even gone so far as to scout out the best spot to leap on a holiday with his parents.
Whatever the truth behind his motivation the authorities are clearly not impressed - they are to charge him with performing an illegal stunt and he could be slapped with a fine of up to $10,000.
Bystanders watched in astonishment on Tuesday as Mr Jones floated by in the Niagara River and plunged 54 metres (180 feet) down the Canadian side of the falls - known as the Horseshoe Falls - before pulling himself onto the rocks below.
Eyewitness Brenda McMullen told a local television station: "He just looked calm. He was gliding by so fast. I was in shock really that I saw a person go by."
Not a scratch
The falls straddle the border between the United States and Canada, and the Niagara River rushes over them at a rate of 150,000 gallons per second.
"I was in the water for about eight seconds... I was
immediately enveloped by what seemed like tons of water," Mr Jones said of the experience.
After his plunge, Jones pulled himself on rocks and waited to be rescued
His story was made all the more amazing by the fact that Mr Jones survived with barely a mark on him.
Captain Shawn Bates of the Canadian Fire Department was one of the first to reach him as he scrambled to safety:
"No scratches, no blood, nothing, He was just wet and starting to get cold, but that was it," he said.
Rescue workers reported that Mr Jones seemed remarkably unperturbed by his fall, although he did stop to scoop up handfuls of moss which he declared would be souvenirs.
Guinness records plan
Mr Jones' relatives claim he had been intrigued by the idea of jumping over the world famous falls for many years and that this had become a growing obsession in recent weeks.
"He said he always thought there was a spot you could
jump and survive," his mother Doris Jones, 77, told The Associated Press. "We never agreed to it. We thought it was risky."
His brother Keith Jones, who shares a home with him in Canton, Michigan, said Kirk wanted to make it into the Guinness Book of Records and had been talking about the stunt for weeks.
"He told me he was going to do it, but I didn't believe it," he said.
There was similar disbelief among Mr Jones' friends:
"No-one believed he would actually do it. He said, 'If I go over and I live, I am going to make some money,'" according to Eric Fronek, another Canton resident.
Although the police say they have discounted suicide as a motive, Mr Jones' father Raymond Jones told the Detroit Free Press that his son had been troubled lately.
He was unemployed, having been laid off from the family business - a small precision tool-and-gauge company, and frustrated by his parent's move to Oregon last week, where they have retired.
"I don't know... if life became so boring, he wanted to change his life," said Raymond Jones. "I guess he has. I don't know whether he has for the better."