Viggo Mortensen takes being a cool actor to extremes. For his new end-of-the-world drama The Road, he had to jump into a very cold ocean on location in Oregon. One wonders: Why can't the world end in, say, Miami?

"That water was cold," says Mortensen. "They had ambulances standing just in case. Of course, I asked for a second take and everyone was shocked because it was also 41 degrees outside in a howling wind."

Mortensen stars in the film, which was adapted from Cormac McCarthy's novel about a man trying to survive with his young son in a postapocalyptic world.

How do you prepare to survive the end of the world?

I tried to do things that I thought would be helpful, like listening to certain kinds of music while keeping in mind where we were headed visually. I had to get into a certain state where I could go to those places that this character demanded emotionally. In the end, there wasn't anything I could do to prepare for the end of the world. It was about being naked emotionally and just being honest about it. I knew that I would really need some help from the boy in the movie and kept thinking, "I hope they find a great boy." I read with the last four or five boys and then the young man cast [Kodi Smit-McPhee] was a ray of sunlight. There was something about him. He understood the story in a way that the other kids didn't. There was something in his eyes. He's a joyful, well-adjusted kid, but there was something in his eyes that was sad and knowing.

Are you a hands-on dad?

I've always been a hands-on dad. I thought about my son quite a bit while making the movie and the transition that he made into pre-adolescence. My son reminds me of Kodi a lot. He's also wise beyond his years. In this movie, you see the kid calling on his dad for strength, but the dad can't always be strong and have all the answers. I guess that's universal. Any parent that has a relatively consistent relationship with their kids, no matter how good it is, reaches a point in pre-adolescence where they suddenly look at their dad or their mom and realize they're not everything.

What did you learn from your discussion with the book's author, Cormac McCarthy?

I talked to him one long time before shooting on the phone. We basically talked about his kid and my kid and being dads. I had tons of notes and questions to ask him. I was ready to pick his brain. At the end of the conversation, he asked me, "Do you have any specific questions about the book?" I had 50,000 post-it notes in the book and not one but two pens in case it ran out of ink. I mean I was ready. But I said "Nah, I don't really" because I realized the conversation we had was all I need to get going. His book and his words are so heartfelt and so free of any gimmickry. He just transcends cultures and languages.

How are your survival skills? Could you camp out? Gut a moose?

Actually, I'm not bad because I go camping quite a bit. But I don't know if I would have had the courage to keep going when it looked impossible. I like to think I would and I'm actually better with a gun than he is in the movie. He's not necessarily good with guns, but he has learned to do what he needs to survive. I know I could survive the camping out part. That's all.

After living in a post-apocalyptic world in this movie do you ever worry about this happening to the human race one day?

Sure I do. We shot in real places that had been devastated by nature and by man. Of course, you're going to think, "Wow, we have to be careful." This movie really made me think more about my family and just about how fleeting life is and that it's worth making the effort to see more, learn more, to appreciate more. It's a very simple idea, but so important.