It's clear to everyone on the Pequod that each day is bring them closer to Ahab's goal. They meet the Rachel, searching for a whaleboat lost in an earlier chase for Moby-Dick. Ahab is so feverishly intent on his own search that he ignores the Rachel's pleas for help, even when he learns that the missing boat carried the captain's 12-year-old son. They meet the sadly misnamed Delight, which just lost five men to the whale. That night Ahab sniffs the air, sensing the enemy is near, and in the morning he's lifted to the tallest mast of the ship to see a round, white hump in the ocean-Moby-Dick.

The chase begins. On the first day the great whale snaps Ahab's boat in two. On the second day the whale's flukes (parts of the tail) smash three whaleboats. As the rescued whalers regroup on the Pequod they notice that Ahab's harpooner, Fedallah, is missing-grim news for Ahab, because Fedallah had predicted that the captain would die only if Fedallah met death first. Yet when Starbuck pleads for him to stop the chase, Ahab answers that he was fated to fight Moby-Dick.

The third day dawns fine and fair. Again three boats are lowered. As Moby-Dick rises, Ahab sees Fedallah's body lashed to the whale-the fulfillment of another condition for Ahab's death. The whale's churning tail smashes Stubb's and Flask's boats so they must return to the Pequod, it sends one man in Ahab's boat overboard. Still Ahab steers toward the whale. But Moby-Dick turns away. And as the men on the Pequod watch in horror, the whale swims mightily toward them, ramming its massive head against the bow. The ship is ripped open, and the sea rushes in. Flask, Stubb, and Starbuck shout helplessly as they are pulled into the water. Deprived even of a captain's privilege of going down with his ship, Ahab hurls a last harpoon at Moby-Dick. In fulfillment of Fedallah's prophecy, the line wraps round Ahab's neck and yanks him, strangled, from his whaleboat into the sea.

The sinking Pequod becomes the center of a whirlpool that pulls every plank, oar, and man into the depths with Ahab. Every man, that is, but one-Ishmael, the narrator, who was the man earlier thrown from Ahab's boat. He survives by clinging to a coffin made for (but never used by) his friend Queequeg. For two days Ishmael floats, lost, in the ocean, until he is rescued by the Rachel. And so he survives to tell his tale.