Pi Patel is a survivor. During his emigration from India, the boat carrying his family (and many of the animals from their zoo) capsizes, and Pi is stranded on a lifeboat, where he struggles — in the company of a full-grown Bengal tiger — to survive for several months until finally running aground in Mexico.

Warning! The following paragraphs contain spoilers.

The "unreliable narrator" is a difficult gambit to pull off, especially in a novel with only one human character, and although Martel succeeds better here than, for instance, Eco did with Baudolino, the result is not entirely satisfying. Throughout the bulk of the novel, the story of Pi's voyage with Richard Parker (the aforementioned tiger) is stated as fact, and the details are sufficiently realistic (even though the story is at times quite farfetched) that the reader suspends disbelief and drifts along with Pi across the Pacific.

For me, this suspension succeeded until Pi landed on the "carnivorous island"; this section strained Pi's credibility as a narrator sufficiently that I lost faith in the novel and really began to wonder what Yann Martel was up to. It was only in the last twenty pages, when Pi tells a different version of the story to the authorities, that things began to make sense. The animals on Pi's voyage were stand-ins for humans, and Pi's story is entirely metaphorical — actually, allegorical is probably a more appropriate term.

My wife disagrees with my interpretation. She thinks Pi's story about the tiger was "the truth" and that the alternate version was simply "telling the authorities what they wanted to hear". Perhaps that says more about my wife and me than it does about the novel.