Goat Island is the island on which Luffy and his crew get lost when they were chased by Marines. They got lost in the fog and discovered this island. There is a partially constructed ship on the island.
The Straw Hat Pirates were chased by three Marine ships. When the Marines' ships were attacking the Going Merry, Nami gets worried but then Zoro tells her to look forward and see that there is a fog ahead of them with a whirlpool and many reefs. Nami decides to go ahead toward the dangerous waters to lose the Marines. The Marine ships follow them into the fog, but one of the ships crashes into a reef while the others crash into each other. The marines then inform their captain Minchey that these waters are a Class - One Danger Zone and going after the Straw Hats is impossible. They argue about pursuing the Straw Hats and then finally decide to withdraw and turn around.
When the Straw Hats arrive at Goat Island, they see a young goat on the shore. Sanji, Usopp, and Luffy chase it to eat it but the goat manages to get away. As they were chasing the goat, they got lured and surrounded by other goats. Chopper found out that it was a trap set by an old man who was in hiding. When they found the old man, the crew chased him down and Zoro used his sword to cut down the branches to capture the man. Due to the sudden attack, the man fainted and then the crew, with the help of the goats, took him back to his house.
When the old man woke up, he asked the crew to compensate for making him faint and he started to order the crew around, making them do chores. When Zoro goes around looking for food, he finds a pirate boat up the mountain and informs the crew. The crew started wondering why there is a ship on top of a mountain, but decided to leave the island instead as they were fed up doing the man's chores. But Chopper said that they should stay, as he had found out that the old man didn't faint because of the sudden attack, but because he only has three days left to live. The crew decided that they should stay and help the old man. They even helped him build the boat that belonged to him.
After the three days had passed, Zoro noticed that the old man was still alive and healthy despite what the Chopper had said and then told the crew that they should leave the island. Nami then reveals to the crew that she lost the ship to the old man over a game of chess. When they go back to talk to the old man regarding this, he tells them that they should work for him for ten years, and only then can they win their ship back. Robin challenges the old man to a game of chess and wins their ship back.
At the Marine Headquarters, Minchey found out that many years ago, Zenny, a pirate money lender, was lost in the foggy waters after stealing from pirates and should be dead by now. Minchey decided to set a trap so that he could get his hands on Zenny, his treasure, and the Straw Hats as well. Meanwhile, on the island, a celebration is going on and Nami asks the old man about his treasure. The old man reveals that he is Zenny, a money lender. Zenny told the crew how he wanted to become the King of the Pirates but he is too old to go on an adventure. Luffy tells the old man that it is never too late to start new adventures.
The next morning, the Marines arrived on Goat Island and the crew prepares to fight them. Minchey says that there is no point in fighting as the crew only had one ship and the Marines had three. Meanwhile, Usopp goes up the mountain to tell Robin about the situation. Nami became suspicious of how Minchey knew that the old man’s name was Zenny as they had not mentioned it in front of him. The Marines got a hold of Usopp and held him hostage and meanwhile, Chopped smelt gunpowder and said that it didn’t belong to only one ship.
Zenny’s boat landed on the sea near the Marine ships where Minchey tried to kill his own subordinate who said that they should take Captain Moore’s assistance, this was the person who informed Moore about what Minchey had done. With the help of Luffy, Zenny, and his goats, they were able to attack the Marines. The rest of the Straw Hat crew had also helped them to fight. Meanwhile, Zenny started becoming weaker due to his heart. This gave Minchey an opportunity to attack. Just as Minchey was about to attack Zenny, Robin, who was present on Zenny’s boat, threw an abacus at Minchey. The Straw Hats then tied Minchey up. Once again, Nami asked Zenny about his treasure, who said that when he landed on this island along with his treasure which was converted to cash, the goats ate all of it. This is the reason why he had said that the goats are his treasure.
Luffy threw Minchey on Captain Moore’s ship, who took away his title after he found out about his betrayal. The crew said their goodbyes to Zenny and left the island. To repay the Straw Hats for capturing Minchey, the traitor, Captain Moore allowed them to choose their battle location. Luffy pointed to a foggy area, which caused Captain Moore’s ship to land in a ship wreck due to the rocks.
A. The Goat Island Arc is the third filler arc of the anime.
A. Yes, there is one person who lives on Goat Island, and that is Zenny, the pirate money lender.
A. The Goat Island Arc lasts from episode 136 to episode 138.