Mamaji is a term that translates to "Honored Uncle," and it is Pi's nickname for Francis Adirubasamy, who was a close family friend to Pi's parents. Mamaji is a world class swimmer, and relates much of his life philosophy with swimming. Though Pi's father has no personal interest in it, he becomes oddly reverent in regard to the world of professional swimming, and greatly admires Mamaji. Pi's full name, Piscine, is actually taken from the Piscine Molitor, a pool and hotel complex in Paris. Mamaji states that the Piscine Molitor is the greatest pool in the entire world due to its clear, pristine, and pure waters.
The significance of Mamaji's stories about the pool concerns how they relate to being Pi's namesake. It very greatly hints at Pi's contentious relationship with water, and how water will come to represent a very real threat to his well-being. Like the pool, Pi is also very clear and pristine in terms of his spirit. He explores several faiths, all as a means of becoming closer to the truth of his relationship with God. Pi's spirit is tested far more than most people, and yet through it all he remains of a clear spirit. Just as Mamaji says at the beginning of the narrative, Pi's story is one that could make anyone "believe in God."