The deal was we had to have people accompanying us and they would ask us not to film something [in North Korea]. For example, we wanted to film at a certain place and there happened to be a building under construction and it didn't look as fancy as the other buildings, so they wanted us to shoot where everything looked finished and made a good impression of the cityscape.

I have made 70 or so films. In all my films not a single actor, a single extra, was hurt. Not one. So statistics are on my side when I say I'm clinically sane.

I'm reminded of an interview Larry King had on his talk show with one of Michael Jackson's sisters. He's talking about how many millions she made on her latest record, and all of a sudden, she looks at him tearfully and says, "Larry, you know, I'm not interested in money or sales or songs. I'm a spiritual person." And I thought, "Oh my god..."

I was able to persuade them to let me shoot in areas that were beyond the volcano itself. Beyond the joint scientific program between Cambridge University and North Korean scientists. I was able to film in a kindergarten, subway, other things you would not normally be allowed to do.

I try to be after something that is deeply reverberating inside of our souls, some deep echo from - even from prehistory. What makes us humans? How do we communicate? Where are we going at this moment? Something for an audience where they can step outside of themselves, where they can be almost like in ecstasy of truth, some sort of deep illumination. And that's what I'm trying in documentaries and in feature films.

We haven't seen a real volcanic event at least in 74,000 years - [Mount Toba] in Indonesia, in Sumatra, where the crater itself is 100 kilometers across. It was so monumental, what happened, that for a very long time the entire atmosphere of our planet was darkened. It's not the lava and the heat per se; it's the obscuring of the entire atmosphere, and it made it very difficult for the human race to survive.

I prefer to be alive, so I'm cautious about taking risks.