In Yann Martel's novel The Life of Pi, swimming is important to the title character because of his uncle. He wasn't his biological uncle, but a good friend of the family's. Pi grew up calling him "Mamaji," which is a combination of the word for uncle and the suffix "ji" which indicates respect and affection.
Mamaji, whose actual name is Francis Adirubasamy, was a champion swimmer. The reason Pi was named Piscine, which is French for swimming pool, is because of Mamaji's passion for swimming.
As a child, Pi went with Mamaji to the pool three times a week. Pi was his willing apprentice as Mamaji taught him all he knew about swimming. Pi's father loved to hear Mamaji's stories, which always had to do with swimming. For Pi's father, it was a lovely escape from his everyday life. Here is the quote from the book that explains how Pi was named:
But no swimming pool in Mamaji's eyes matched the glory of the Piscine Molitor. It was the crowning aquatic glory of Paris, indeed, the entire civilized world. "It was a pool the gods would have delighted to swim in. Molitor had the best competitive swimming club in Paris. . . .The showers gushed hot, soothing water. There was a steam room and an exercise room. The outside pool became a skating rink in winter. There was a bar, a cafeteria, a large sunning deck, even two small beaches with real sand. Every bit of tile, brass and wood gleamed. It was—it was. . ." It was the only pool that made Mamaji fall silent. That is how I got my name when I entered this world, a last, unwelcome addition to my family, three years after Ravi: Piscine Molitor Patel."
The significance of swimming in this novel is not just about how Pi was named, but also sets the stage for how he was able to survive such a shipwreck. His swimming skills were strong, and he had been taught by the greatest swimmer in all of South India for his entire childhood.