Bear Grylls has spoken of how President Barack Obama flouted the protocol of his secret service to take up every challenge thrown at him, when he appeared on the survival guru's television show.
The British ex-SAS soldier and television host said Obama's security team were on tenterhooks, as he and the President spent the day trekking through the Alaskan wilderness filming a special episode of Running Wild.
"It was different show to normal due to the 60 or so Secret Service agents and helicopters hovering above," Grylls told the Absolute Radio Christian O'Connell Breakfast Show.
"But [Obama] was so down to earth and couldn't have been nicer."
The secret service had spent time laying down the rules of what Grylls could and could not do with the President: "It's funny, they said lots of things beforehand," he said.
"For example, if he was eating anything, then it had to be approved by his chef, as did anything he drank, and that he couldn't do anything too dangerous, but on the day I decided to just wing it."
But as soon as the day began, the survival expert said, he realised that the President "really wanted to get stuck in".
"I found an old fish that a bear had munched on beforehand and cooked it up for him. We shared water bottles, food...everything," he said.
The survival expert then proceeded to lead Obama down a mountain: "We were going down this steep slope and the secret service were saying it was too dangerous," he said.
"So I told the President that they didn't think he could do it but he was like 'of course I can...I'll show them...c'mon let's go!'
"We ended up doing everything and he loved it. Afterwards, I thought I was going to get a special telling off from the secret service guys, but they all laughed and had a good time."
In the days before the show was filmed, the survival expert had warned that he was going to give America's commander-in-chief the same tough treatment that he gives his other guests.
"I will not deny your suspicion that there may have been some suggestions put forward by the Bear Grylls team that were not approved by the Secret Service," Josh Earnest, the White House press secretary told reporters on Air Force One during the flight to Alaska.
The President's participation in the show, which is due to air on NBC later this year, was part of a three day trip by Obama to the Arctic Circle - the first by any sitting president - which he used to illustrate the urgency of his climate change agenda.
Grylls said he was warned by Obama's protocol staff that he could not give the president any gifts. But at the end of the filming he gave him his knife and said that the President should keep it "as a last line of defence if anybody ever got through the secret service".
"I had a great email a few days later from his team saying that he absolutely loves the knife and he keeps playing with it! Boys love their toys," he said.