There may not be, in the history of seafaring, an instance of a man shipwrecked with a tiger. But that didn’t stop Yann Martel from creating his 2001 novel “Life of Pi” around such an encounter.

It’s relatively easy to write a novel about a man and a tiger sharing a lifeboat, but not so easy to make a movie of such a thing. Oscar-winner Ang Lee gives it a shot, with a digitally festooned film that aims for magic and occasionally achieves it.

The shipwreck story is told to us by the adult Pi, played very touchingly by the Bollywood actor Irrfan Khan (the police inspector in “Slumdog Millionaire”). He’s telling a tale of his youth, how he got the name Pi and how he ended up in the middle of the Pacific Ocean with the aforementioned jungle cat. Pi is played in the main story by Suraj Sharma.

Ang Lee knows how to make big movies (“Crouching Tiger, Hidden Dragon”) and intimate ones (“Brokeback Mountain”), and this is both. There’s a large-scale shipwreck, which might be the most dazzling sequence in the film, and there are also tiny problem-solving issues facing a man in the middle of the ocean.

The movie seeks to explore the nature of humanity, and perhaps also the presence of God. I think it’s actually about the nature of storytelling, and not very much about God, but that might be my reading of the framing story with the narrator, which grows in importance as the film goes along.

All of which is ambitious and thoughtful. But actually watching “Life of Pi” is a curious experience, in large part because the movie would be impossible to shoot without extensive use of computer-generated imagery, especially involving the animals (a hyena, a zebra and an orangutan also survive the wreck).

“Life of Pi” wouldn’t exist without digital effects and green-screen technology, because there’s no way you shoot a movie in the middle of the Pacific with a real tiger. Lee and his technicians whip up a gallery of effects, including phosphorescent ocean creatures, storms at sea and, of course, the big cat, whose name is Richard Parker (long story). All of which is available in 3D in some theaters.

It’s a technical achievement, that’s for sure. And while I was watching those scenes I was mostly thinking of the technical achievement, which can’t be the right way to experience the enchantment the movie wants you to feel.

In fact, I was much more impressed by the scenes of Pi as a middle-aged person, sitting in his home. The real drama actually lies with this man, who has a parable to tell about why we need stories, and why we invent them. Analog or digital, that’s where real mystery lies.

“Life of Pi” (3 stars)

Ang Lee’s 3D digital extravaganza about a shipwreck survivor and a tiger who share space on a lifeboat, adapted from Yann Martel’s novel. For all the movie’s shiny, vaguely unreal effects, the real mystery of the tale comes in the framing story of the man narrating it; the computer-generated stuff pales by comparison.

Rated: PG for violence.

Showing: Alderwood, Cinebarre, Stanwood, Sundance, Cascade, Woodinville.