About the Arlong Park Arc
Zoro, Usopp and Johnny track Nami, who stole the Going Merry, to Cocoyasi Village, her hometown. They discover that it is ruled by Arlong and the Arlong Pirates, a pirate crew of Fish-Men of which Nami is a member. After Luffy and his new cook Sanji arrive on the island with Yosaku, Nami's past and true motives come to light. The Straw Hats decide to free both her and the village from the Fish-Men's claws.
The arc begins following the end of the Baratie Arc, with Luffy, Sanji, and Yosaku heading for Arlong Park on a small boat. To pass the time, Yosaku tells them about the Seven Warlords of the Sea and how this relates to their current destination. When Sanji doubts that Nami is heading there, Yosaku explains that they were able to estimate her course after he and Johnny had suspected the connection between the two before they were thrown off the Going Merry. The two had noticed that Nami had been interested in their copy of Arlong's wanted poster, and her behavior quickly became suspicious when they told her that Arlong recently had become more active. Meanwhile, Nami arrives at Arlong Park in the Going Merry. Once she arrives at the park's gate, a boy confronts her, trying to fight Arlong for the death of his father. Nami slaps him and gives him some money to make him leave. After this, Arlong and his crew are introduced, and it is revealed that Nami is part of Arlong's pirates.
Zoro, Usopp, and Johnny arrive at the island, with the latter two tying up Zoro to prevent him from immediately fighting the Fish-Men. Seeing that two Fish-Men have spotted them, Usopp and Johnny abandon ship, leaving Zoro to be captured by them. They soon find themselves in the remains of Gosa Village, with all the houses upturned. One of the Fish-Men from earlier spots the two and starts chasing them. Johnny manages to escape and hide, while Usopp ends up getting attacked by the same boy from earlier, who had mistaken him for a Fish-Man. However, a woman manages to stop him. Seeing the real Fish-Man getting closer, Usopp readies to fight him, but gets knocked out by the woman, who claims it is not a good idea to fight one of the Fish-Men.
Meanwhile, Luffy, Sanji, and Yosaku continue sailing, and just as they take a break to eat, they encounter a giant sea cow that is attracted to their food. Luffy punches it at first, prompting Sanji to reprimand him for it; but when he realizes the sea cow sees them as food, he quickly subdues it with one kick. The three then strap the boat to the sea cow and use it to tow them to the island.