- "If you're lucky enough to discover one of these courses throughout your journey, you'll have a chance to earn a colossal amount of coins."
- ― New Super Mario Bros. 2's Official Site
Rainbow Courses are special stages in New Super Mario Bros. 2.
How to Unlock
These special levels are unlockable using the flagpole at the end of every normal level. The level must be completed when the last two digits of the timer match the number of the World the player is currently in. After that, a Rainbow Course will appear at the left end of the world, where the arrow level is. Once the level is visited, it will not be available until the player finishes a normal level with the right conditions again.
Appearance and Design
A Rainbow Course always begins with Mario/Luigi being shot into the sky by a Pipe Launcher. The background of the Course is a cloudy sky full of rainbows. All solid objects other than the yellow platform carrying Mario/Luigi are made of multicolored, transparent blocks.
These special levels will give the player an opportunity to collect many coins outside of normal levels. Also, in all Worlds except World 1, collecting Red Coins in a Rainbow Course will give the player a Gold Flower, which is immediately pocketed for later use in normal levels.