Richard Parker killing the hyena, after it killed Orange Juice the orangutan.
The part when that giant whale jumps and throws the boat away. It starts with a magnificent view of the boat in the middle of a luminescent ocean at night. Suddenly, a dark shadows starts to appear in the water and grows more and more until it jumps. And is gigantic and made the boat—and by extension, the viewer—feel like an insignificant ant for a second.