"Life of Pi," Yann Martel's 2001 bestseller about a teenage boy drifting at sea in a tiny lifeboat alongside a tiger, zebra, hyena and orangutan, is an inherently challenging novel to adapt for the big screen. It requires its director to mimic the experience of floating, post-shipwreck, on the vast Pacific Ocean and to tell a story steeped in internal psychological struggle. Then there's the matter of dealing with two things most filmmakers are cautioned to avoid: young actors and potentially untameable animals.

Clearly none of this was too daunting for filmmaker Ang Lee, the soft-spoken Academy Award winner responsible for the elegant reserve of "Brokeback Mountain" and "Crouching Tiger, Hidden Dragon." After signing on to the project in 2009, Lee even added extra challenges to the adaptation process, opting to shoot the film in 3-D with an unknown (newbie thespian Suraj Sharma) as his protagonist.

At this point it's worth noting that Sharma - who, as Pi, lives for an extended period of time on the open water - had no idea how to swim when filming started.

"There's one minute alone, underwater, where he has to hold his breath for at least a minute and a half," Lee says via telephone about his young star. "And I tested him and it was only 15 seconds."

The director laughs about this now, noting that Sharma is "physically very agile" and was a quick study in the art of treading water. (For the record, the 19-year-old can now swim just fine.) Lee gets more serious when discussing the other issues he confronted; for example, while discussing his adjustment to 3-D - a medium in which the director had never worked until "Life of Pi" - he uses the word "confusing" three times and "elusive" twice.

"Three years back, I didn't know what it was," he says. "I just imagined that with a new medium, maybe, just maybe, it opened up new chances. And as I got into it, I found this is truly a new cinematic language. It's confusing because we're not used to it."

If Lee was confused, it doesn't show onscreen. Like other acclaimed directors who have recently taken the multidimensional cinematic approach - Martin Scorsese, Wim Wenders and Ridley Scott among them - Lee's use of 3-D comes across as less as a gimmick and more of an organic element, one that effectively emphasizes the sudden horrors of Pi's increasingly dangerous situation and the surreality of a life adrift at sea.

At this point, readers of "Life of Pi" may be wondering how Lee managed to throw a SAG-card carrying human being into a glorified dinghy alongside those aforementioned creatures.

The short answer is CGI. The longer answer is that, particularly for the Bengal tiger with the unusual, personifying name Richard Parker, a combination of real animal footage, computer-generated images and scenes shot in a huge water tank in front of a green screen were seamlessly blended.

The result is that the starving, desperate Pi and the ferocious predator from his family zoo really do seem to come in close physical contact as they spar over personal space.

Lee says he spent months supervising the evolving work of the CGI wizards to make sure everything turned out just right, another aspect of the job that made this a more methodical endeavor than his previous work.

"I got very technical on the movie 'Hulk,'" he says, "but I think by percentage and probably degree of difficulty, yeah, this is my most technical" film.

On "Life of Pi," even some of the more traditional elements of cinema presented hiccups.

Throughout the film, there are numerous scenes in which the adult Pi (Irrfan Khan) tells a writer the story of his perilous adventure. That writer was originally played by Tobey Maguire, who previously worked with Lee on 1997's "The Ice Storm." After shooting all of that footage, Lee decided he needed to recast the role with a lesser-known performer because Maguire's presence was distracting in a field of mostly non-boldfaced actors. The scribe is played in the final cut by Rafe Spall.

"With somebody like Tobey," Lee explains diplomatically, "I think I underestimated his star power. I knew Tobey when he was young, and he's a great talent, so I forgot how powerful he is as a star now."

Despite the issues involving his cast, both the humans and the computer-generated members, Lee says he's game to attempt a similarly ambitious film in the future, particularly in 3-D.

"If it's an independent, smaller movie, I won't do it because it is not possible," he explains. "You want it to work for you, not you to work for it. But if budget allows and it's a reasonable budget, I would do it again because I am curious to find out what it really is, to find new film languages."

"2-D," he laughs, "everyone knows everything."