From Bulbapedia, the community-driven Pokémon encyclopedia.
Mirage Island (Japanese: まぼろしじま Phantom Island) is a hard-to-reach location in Hoenn.
In the games
Mirage Island is found on Route 130 in Pokémon Ruby, Sapphire, and Emerald. However, it can only be visited under highly rare circumstances. The island is inhabited by wild Wynaut which range from level 5 to level 50. Most notably, the island also bears a tree where the one and only Liechi Berry in the game can be picked. This is the best Berry for Pokéblocks, and will produce Gold Pokéblocks.
Every day, a random number between 0 and 65535 is generated by the game. If this number matches the last two bytes of the personality value of any Pokémon in the player's party, then Mirage Island will appear. (Consequently, Mirage Island can be made to disappear and reappear for that day by removing and putting back the matching Pokémon in the party, and Mirage Island will disappear at the end of the day barring the unlikely outcome of two matching numbers being generated in a row.) This makes Mirage Island's appearance even rarer than encountering a Shiny Pokémon, although the probability increases with the number of Pokémon the player has. The odds of a single Pokémon activating Mirage Island is 1/65536; this chance is increased to approximately 1/10923 if the player has a full party.
A man in the northeastern hut in Pacifidlog Town will tell the player whether or not he can see Mirage Island, allowing the player to check if they have a matching Pokémon without having to leave the town. Since Mirage Island's number does not change throughout a given day, it is possible for the player to freely move Pokémon between the boxes and the party while attempting to check if any Pokémon in the party matches the Mirage Island number.
Two random bytes ("Mirage Island bytes") are generated for the day once any button is pressed on the start menu, and will last until the start menu is accessed again past 00:00 (midnight) of the next day. Even though play time has nothing to do with the real-time clock, a game that has reached the maximum time of play (999 hours and 59 minutes) will always generate Mirage Island bytes of 0. Additionally, if a game's internal battery is dead (causing the real-time clock to stop functioning), then new Mirage Island bytes will never be generated, causing the Mirage Island number to permanently stay at whatever value it was before. Currently it has not been precisely documented what happens to a game which has both a dead internal battery and a maximized play time.
Route 130 with Mirage Island
Route 130 without Mirage Island
|| 5, 10, 15, 20, 25, 30, 35, 40, 45, 50
| A colored background means that the Pokémon can be found in this location in the specified game. A white background with a colored letter means that the Pokémon cannot be found here.
In the anime
Mirage Island in the anime
In Who, What, When, Where, Wynaut?, Ash, his friends, and Team Rocket landed on Mirage Island after Team Rocket's submarine exploded. May and Drew were stuck together and both ended up nearly drowning when Drew passed out, before being saved by the resident Wynaut population.
While the island does appear on maps, the whirlpools around it make it almost impossible to get to or from the island.
In the manga
In the Pokémon Adventures manga
Wally rescues the man searching for Mirage Island on Pacifidlog Island from being washed away from Kyogre's storm.
Ruby and Sapphire were washed up on Mirage Island, after meeting up with Juan, Tate and Liza, Juan explains that the time in the island is different from the external world and they were unconscious in the island for twenty-one days. The time on the island does not always travel at a constant speed and when the time on the island goes normal, one can get on or off the island, so Juan carries a Sandshrew-shaped hourglass for this reason. Ruby and Sapphire meet up with Plusle and Minun for the second time and use them to practice Double Battles with Tate and Liza, preparing for the final battle against Kyogre and Groudon.
According to Juan, Mirage Island is not the actual name of the island; rather, this is what people call the island.
In other languages