Mirage Island can be seen by the player when the personality value of one of the Pokémon of the player's team matches the random number between 0 and 65535 which is generated by the game every day. A man in one of the houses in Pacifidlog Town alerts the player as to whether or not Mirage Island can be seen and if the player can go there.
In the Pokémon Adventures manga, Ruby and Sapphire trained on Mirage Island along with Juan, Tate, and Liza. According to Juan, time in Mirage Island does not flow in accordance with the outside world and carries a sun-dial on his person so he can actively estimate how long they have been on the island.
All Wynaut caught on Mirage Island will display Found on Route 130 as the location where it was caught.
Caves, Tunnels & Mountains
Rusturf Tunnel · Island Cave · Granite Cave · Desert Ruins · Jagged Pass · Fiery Path · Mt. Chimney · Meteor Falls · Scorched Slab · Ancient Tomb · Mt. Pyre · Shoal Cave · Aqua Hideout · Magma Hideout · Seafloor Cavern · Cave of Origin · Sky Pillar · Victory Road · Sealed Chamber · Artisan Cave E · Desert Underpass E · Marine Cave E · Terra Cave E
|Kanto (Sevii Islands) · Johto · Hoenn · Sinnoh (Battle Zone) · Unova · Kalos · Alola|