After becoming an overnight sensation thanks to his major roles in two of cinema's biggest franchises, Lord of the Rings and Pirates of the Caribbean, the Brit was exhausted after promoting Pirates of the Caribbean: At World's End and needed to escape the limelight.
He joined his cousin on a research trip to Antarctica on a Norwegian icebreaker for two months, and admits getting stuck in with the rest of the crew brought him back down to earth.
He tells Britain's Live magazine, "When I finally finished doing the press tour for the last Pirates movie in 2007, I just didn't know which way was up. I genuinely felt quite discombobulated. Not in a bad way. I was tired. I needed to do something different. I needed to regroup.
"My cousin (Sebastian Copeland) is an environmental campaigner and photographer and he was doing a book called Antarctica - A Global Warning. He joined the research ship and I went along and assisted him. There was no phone, no email...
"I needed to take stock and get my bearings. I had been working on one project after another. I just wanted to let it all sink in. I had to turn down work to go on the trip, but I've come to believe that everything is cyclical. Every great actor I've worked with has been conscious of the same thing - you have your moment, you have a wave that sweeps you up and then you have to paddle a bit and stay sharp for when the next wave hits you."