After leaving Warship Island the Going Merry is now towards the Grand Line, and the crew now returns to the Great Adventure.

Upon entering the Grand Line, the ship is swallowed by a giant whale, inside of which they discover a strange place. In addition, they are not the only ones there.

After hearing the story of Laboon the whale, Luffy comes up with a clever solution to his problems. From Laboon's caretaker, Crocus, the crew learns more about the Grand Line and how to navigate through it, since compasses are useless there.

Luffy and friends arrive at Whisky Peak, a town of pirate-lovers who hold them a feast.

Zoro battles a hundred members of Baroque Works, and discovers there is more to them than meets the eye.

Luffy, who does not realize the town is full of bounty hunters, engages in a battle with Zoro after he discovers that Zoro attacked the townsfolk, while Mr. 5 and Miss Valentine head for Princess Vivi.

Luffy's crew manages to become targets of Crocodile, one of the Shichibukai, and decide to help Princess Vivi. They also meet Miss All-Sunday, the second strongest member of Baroque Works and partner of Crocodile.

As Luffy and his crew are sailing in the Grand Line, Koby and Helmeppo are stuck doing odd-jobs for the marines back in East Blue, and encounter Vice-Admiral Garp.

Vice Admiral Garp mentors Koby and Helmeppo to become marines.