Rainbow Mist

The Rainbow Mist (虹色の霧, Niji-iro no Kiri) is a mysterious fog that is in fact a gateway to another dimension and it is impossible to know when and where the Rainbow Mist will appear, however, it appeared twice near Ruluka Island while no appearances in other places were reported.

Any ship who enters the Rainbow Mist is automatically transported to the dimension Ape's Concert (エイプスコンサート Eipusu Konsāto, Wrecker's Reef in the 4Kids dub) in which all ships and their crews and passengers are trapped when they entered the Rainbow Mist, It is called also a ship's graveyard because it is filled with wrecked ships and it is said that there are many treasures in their cargo.

Also, it seems this place is an space loop, which means it takes anyone back to the point in from which they started as shown when Robin fired a cannon ball from the front of the Going Merry only for it to land close behind the ship and Time does not seem to pass here or it passes much slower than normally, however by the time the Pumpkin Pirates entered the mist, none of the previous prisoners were there, the reasons behind their deaths are not clear, but it is possible that they were eaten by the Ruluka Sea King, a beast that was also trapped in Ape's Concert.

First appearance: Episode 139.

History
At some point in the late 1460s a Marine ship commanded by Rapanui's father entered the mist and was trapped there, eventually the entire crew died there like the crews of all other ships before them.

Around 1472 the Pumpkin Pirates and Ian, a member of the Wetton Pirates, were trapped in the Rainbow Mist during Wetton's attack on Ruluka. For the next fifty years Henzo, the only member of the Pumpkin Pirates who stayed back on Ruluka, researched the phenomenon in order to rescue his friends. Wetton, who became the mayor of Ruluka sponsored his work.

A book series entitled Rainbow Mist, Volumes I through X was written around 1482. According to the book series, the Rainbow Mist should lead to the Land of the Gods or El Dorado, It also says that everyone who has looked for the Rainbow Mist and the Land of Gods has never returned and that its inhabitants live forever without aging or going hungry. Nico Robin obtained the first nine volumes in Alabasta shortly before she joined the Straw Hat pirates.

In 1522 the Straw Hat Pirates visited Ruluka Island and met Henzo. On Ruluka Island, some of the Straw Hats made enemies of the mayor and his men, who had placed high taxes on everything. Robin, Usopp, and Luffy meet Professor Henzo, who is doing research on the island's Rainbow Mist. When some of the mist shows up, Henzo borrows the Going Merry to go explore it. The Going Merry, with all crew members but Sanji, Nami, and Chopper aboard, gets caught in Ape's Concert. They find out that the inside of the Rainbow Mist is full of wrecked ships and treasures, including ones not found in the current time period and is guarded by five kids. The kids are actually friends of Henzo's that got lost in the mist over fifty years ago. Henzo, his friends, and the others try to find a way out of the ship graveyard. Meanwhile, the mayor and his men let the information about the Rainbow Mist slip to the remaining Straw Hats still on Ruluka. Luffy accidentally propels himself and Rapanui Pasqua to the end of the mist. Nami appears in the ship graveyard with a rowboat full of treasure and a rope connected to a dock in the real world, which is stolen by Wetton's subordinate. The mayor uses the Rainbow Tower to make a bridge to the Rainbow Mist. Due to the destruction of the Rainbow Tower, The mist collapsed. However, the Straw Hat Pirates and the Pumpkin Pirates managed to escape its destruction, each crew returning to their own time period. The Going Merry escapes from the Rainbow Mist, getting badly damaged on the way. The mayor gets arrested by a bunch of powerful Marines that turn out to be older versions of Henzo's friends, who were thrown fifty years into the past by the Rainbow Mist's collapse.

List of prisoners

 * Pumpkin Pirates
 * Rapanui Pasqua
 * Isoka
 * Pukau
 * Longo
 * Akibi
 * Henzo


 * Straw Hat Pirates
 * Monkey D. Luffy
 * Roronoa Zoro
 * Usopp
 * Nico Robin
 * Nami


 * Wetton Pirates
 * Ian


 * Marines
 * Rapanui's Father


 * Ruluka Sea King


 * Ships:
 * Tarielishin
 * Going Merry

Trivia

 * "Ape's Concert" is a pun on the Sargasso Sea - saru means monkey or ape, and gassō means ensemble in Japanese.
 * It is likely based on the fairy realms in the Celtic religion, where time moves more slowly than in the real world.
 * Nico Robin is seen reading a book titled Rainbow Mist in Episode 131.