The Momoiro Island is an island on the Grand Line. The island is filled with pink animals and plants. It is home to the Kamabakka Kingdom (カマバッカ王国,Kamabakka Ōkoku?, "Kamabakka Queendom" in the Viz Manga), a place where "those with a heart of a maiden" gather. The name of the kingdom literally translates to "full of transvestites", which is exactly what the island is filled with.
Sanji was sent here by Bartholomew Kuma during the events of Sabaody Archipelago. Due to the maniacal nature of the transvestites inhabiting the island, Sanji considers the place to be 'Hell', but still spent two years on the island honing his skills.
The island and its inhabitants is just as well known as the legendary island of Amazon Lily. However, the islands are exact opposites of each other. While Amazon Lily is comprised only of women who behave somewhat similar to men (similar to the Amazons of lore), Momoiro is filled only with men who behave similar to women (usually the behavior of a transvestite), even the animals are transvestites. Nevertheless, like its counterpart, the island's population seems to be comprised of powerful fighters who abide and appear to be totally comfortable with their lifestyle, mostly due to their famous power-enhancing Attack Cuisine.