World S

"Wow! Can ya believe it?! This must be that strange, legendary world we've been hearing rumors about! There are even more Power Stars around here! So! Let's go get 'em, Captain!"

- Lubba

World S: Here We Go!, also known as Special World, is the seventh and last world featured in Super Mario Galaxy 2. It is located high in the sky of an unknown planet with colorful star-shaped islands, and has two rainbows in the background. This world is shaped like an "S", hinting at its name, and has no forked directions. It holds a total of seven galaxies, the last of which, the Grandmaster Galaxy, can only be accessed by collecting all 120 Power Stars as well as all 120 Green Stars. It is unlocked after the player defeats Bowser for the first time. This world's appearance is hinted at by a Bob-omb Buddy brought back from the Throwback Galaxy, who asks about the "strange, legendary world" in a manner similar to Lubba's.

Galaxies

 * Mario Squared Galaxy
 * Rolling Coaster Galaxy
 * Twisty Trials Galaxy
 * Stone Cyclone Galaxy
 * Boss Blitz Galaxy
 * Flip-Out Galaxy (Hungry Luma)
 * Grandmaster Galaxy

Trivia

 * This world's music is a slower rendition of Gusty Garden Galaxy's music from the previous game Super Mario Galaxy.
 * All the galaxies in this world except Flip-Out Galaxy are references to previous Mario games. Mario Squared Galaxy, Stone Cyclone Galaxy, Boss Blitz Galaxy and Grandmaster Galaxy (in the case of The Perfect Run, because of the music) are references to Super Mario Galaxy, Rolling Coaster Galaxy is a reference to the Rainbow Road courses from the Mario Kart series and Super Mario 64 (because of the music), and Twisty Trials Galaxy is a reference to "The Secret of Ricco Tower" from Ricco Harbor in Super Mario Sunshine.
 * This is the only world in the entire game where every galaxy has two regular missions, and all but one have two Green Star levels.
 * No galaxy in this world has a Teleporter that leads to a Bonus Planet.