Chris Hemsworth was banned from surfing a 40-foot wave for his new TV show over fears he would drown

He told The Hollywood Reporter: "I was going to attempt to surf a 40-foot wave and train with big wave specialists, but we couldn't get it through the ranks.

"The risk assessment, basically, was too far gone, so I ended up climbing a 200-meter dam wall,.

"They both have a fair amount of risk attached to them, but [the dam climb] got past the risk assessment team. So there definitely was [concern]: 'No, we need him to go off and shoot Thor next. We can't have him drown while filming a big wave episode'."

Hemsworth went on to reveal he only gave him two weeks to learn a song on the drums before performing with Ed Sheeran at a gig in front of 70,000 fans - and he now wishes he'd given himself more time to practice.

He explained: "Well, the truth is I didn't [cancel all my plans]. I should have canceled a whole lot more. I was in and out of a press tour at the time. I had other work obligations. I have three kids, and I couldn't cancel them, so they were still there ...

"I would've liked to have sent them off somewhere else for a couple of weeks and applied my complete focus to this, but I wasn't able to do that ...

"I had about six-to-eight weeks to learn, and I kept putting it off. And about two weeks out, I realized I didn't know the song. I was in the space of no return. It was too late basically."

The actor spent two weeks working hard on his drumming and ended up with blisters all over his hands. He admitted the experience of performing with Sheeran at the gig in Bucharest last year was "terrifying" but he was "thankful" for the experience.

He added: "70,000 people were singing along in unison and moving to this beat, this track, this song, this artistic creation that Ed assembled, and I was a piece of that puzzle. It felt how universal prayer or meditation or something on a big global scale might feel like ...

"It was pretty special. I'm very thankful for it."

Limitless: Live Better Now lands on Disney Plus/Hulu on August 15 and airs on National Geographic on August 25.