"It was very painful, not being able to breathe for a long time," he remembered of his time beneath the water.
"It's like you're in an avalanche, and you don't know if you're ever coming up, and you can't breathe and there's nothing you can do about it. You think, 'Why did I do this, what was I thinking?' And it's too late.
"I know there are a lot of people who had those thoughts and never made it back up.
And I did make it back up, but then it all started all over again because nobody could get to me, so I went down again twice, and that really put the fear of god into me. And that's when I went, 'Ok, this is getting stupid.'
Butler has been oft-ready to throw himself into the action, since he came to stardom in '300'. But now the Scottish star reflects it's time to choose the softer option...
"I should protect myself more. I always go in sane, say 'This time I'm going to be more careful'. And then that's fine if you do it once, but after the 15th take, you're cut to shreds. At one point, my arm was black and blue with a kung fu move, which I must have done 300 times or more, and at the time you're not thinking about it, and then two movies later, there's still a chip in your bone, and you think 'why the f*** did I do that?' It's probably time to start using stuntmen more.
"But it's hard because part of the thing I love about this is... you want to get in there, be on that chopper, surfing that wave, holding that gun... doing the sh*t that boys do.
It's not the first time Butler's come unstuck, with the actor describing another time when a car containing him and Pierce Brosnan (in the thriller 'Shattered') went straight into a wall.
"I don't know what happened, but we were on the roof, looking at the edge of a car park, driving full speed towards the edge, my neck went out, I had bruised ribs for months.
"There's always stuff going on but that's the game you choose, and ten years later you're still getting your ribs cracked back in... it's fun. I'm sure they throw some danger pay in. They'd better."