Guppy and the Underground Lake

Guppy and the Underground Lake is the third mission of the Deep Dark Galaxy in Super Mario Galaxy. The mission's objective is to find Guppy and complete his challenge.

Layout
The player must make their way down to the bottom of the underwater cave. There, they will find Guppy waiting on a star-shaped rock, and approaching him will have him challenge the player to swim through eight rings. All eight rings are placed either within a group of enemies or an obstacle. The player can use Green Shells to move through all the rings before they disappear, and failing to move through a ring will cause the player to fail the challenge. Swimming through all eight rings before they disappear will have Guppy give up a Power Star.

Trivia

 * Guppy will act as if he has met Mario, regardless of whether or not he was encountered in the Sea Slide Galaxy.