For other uses of this name, see Goat Island (Disambiguation).
Goat Island is the island where  Luffy first met Koby and Alvida. This island appeared only in the manga, while in the original anime, Luffy met Koby on the Lady Mary. The island was later included in the special Episode of Luffy.
Goat Island as depicted in Episode of Luffy.
It is a small, rocky island where small rocks covered the shoreline and a small forest is visible.
At some point, the
Alvida Pirates made this island their base. After making Koby their chore boy, he planned for years to escape, building a small boat near the forest.
Once Luffy defeated Alvida, Koby was freed, and the Alvida Pirates later merged with the
Buggy Pirates. The bases on the island are presumably abandoned since the crew is currently in the Grand Line.
One Piece Yellow: Grand Elements (p. 20),
The island's name is revealed.