Rainbow Road is a polychromatic section of Mario Land suspended in the starry night sky in outer space. Its long paths are formed of solid light in all the colors of the spectrum. It can be reached only by characters who have the power of flight or who can find someone to carry them. Oddly enough, Rainbow Road is located directly above Elmore, and there are Monkey Skyway Agents available to take players there from here.
Rosalina, Lubba, Polari, and the Lumas have escaped to Rainbow Road after the destruction of Comet Observatory when Lord Fuse started to attack the Earth. Lady Rainicorn helped Rosalina and the Lumas and she spends time on Rainbow Road, too, where she serves to transport players instantly one-way to Sector V.
Rainbow Dash and Darwin were sent here by Dexter to scout out the area, with a view to making it a safe haven for refugees from the Fusion Invasion. Darwin has, astonishingly, proven so successful at battling the Fusion Monsters who were here that the area is now a safe place with no Fusion Matter around it, though he returns here periodically from Elmore to keep the monsters from re-invading.