The novel is named after Moby Dick because he is the center of Ahab's obsession and a key figure in his own right. The White Whale's appearance is unique. He is an exceptionally large sperm whale with a snow-white head, wrinkled brow, crooked jaw, and an especially bushy spout. His hump is also white and shaped like a pyramid; the rest of his body is marbled with white. He has three holes in the right fluke of his tail, and he fantails oddly before he submerges.
The White Whale seems to have an almost human personality, featuring the battle savvy of a bold general. One of his favorite tricks is to seem to be fleeing from hunters but suddenly turn to attack and destroy their open boats. When engaged with the crew of the Pequod, he sounds (dives) and then reappears in their midst before they can escape or counter his attack. When they lodge harpoons in him, he uses the attaching ropes to whiplash and destroy their boats. In a final show of timely brute force, he crashes into the bow of the Pequod itself and quickly sinks her.
These are the facts. Equally important are the legends and suspicions regarding Moby Dick. He is said to be immortal and omnipresent, supposedly appearing in several locations at the same time. Most significant is what he means to Ahab. The captain sees the White Whale as a great mask, a façade behind which is some "inscrutable thing," an undefined power that Ahab resents and seeks to destroy. Each reader must confront this problem: Is Moby Dick a mask for some great force of evil? Is he a figure of nature that hides, perhaps, the face of God? Or is he just a big, clever fish that would leave men alone if they would stop bothering him?