Slimy Spring Galaxy

The Slimy Spring Galaxy is a galaxy appearing in Super Mario Galaxy 2. It is located in World 6 and mostly takes place in water. It makes extensive use of the Green Shell to move around underwater. Common enemies here include Snoodles, Urchins, and Boos. This is the only galaxy in the game that can be accessed only after the player gets a Power Star in a galaxy made out of a Hungry Luma (besides the Grandmaster Galaxy).

Under Ground Dangeon Planet A
The Under Ground Dangeon [sic] Planet A is the first of two very similar planets featured in this galaxy.

The starting section of this planet is a small area made with tile flooring and many rock formations. To the left is a Warp Pipe with three shells and nine treasure chests. Straight ahead from where the player starts are two bats and a slide that takes the player down to the next section.

After taking the slide down, the player will end up in a water filled tunnel with many mines and coins. A Bill Board explains how shaking the Wii Remote near a shell will make the player pick it up. The Green Shell is used here to make underwater travel easier. There are a few Snoodles later in the area and the Comet Medal can be found to the left of the tunnel, in an offshooting area in the wall.

Next is a generally wide area filled with Snoodles and columns. There is a tunnel with Urchins at the end and two Gringills are found at the top of that tunnel. Snoodles are found in the path to the Launch Star which takes the player to the Under Ground Dangeon Planet B. If the player waits until Mario drops from the Launch Star, Mario will land on a secret platform with a 1-Up Mushroom.

Under Ground Dangeon Planet B
The Under Ground Dangeon [sic] Planet B starts off with a single Paragoomba flying over a large hole. When the player jumps down the hole, they will enter another underwater section, with an arrow made of Star Bits pointing in the direction of another underwater tunnel. This one is much longer, and the player must use the Green Shells, rings and Bubbles to get to the end before they run out of air. There are huge walls blocking the sections and the only opening is where the ring is. If the player is still in full speed and he bumps into one of these walls, the shell that the player is holding will get smashed and then disappears. Conveniently, there is a shell in between each wall where the player can retrieve if his shell was smashed. During The Chimp's Coin Challenge, the walls are absent. Boos are bountiful in this area and the coins they drop when defeated can refill the player's air meter. At the end is a long tunnel filled with Urchins that leads outside.

The final location is an outlook area toward a vast plain. It is filled with lush grass, lily of the valley flowers, two trees and two waterfalls east and west of the outlook. There is a single treasure chest in the middle and a Green Shell at the left area. When the player opens the chest, the Toad Brigade Captain will pop out and give the player a star for saving him, similar to the event in the Bigmouth Galaxy from Super Mario Galaxy..

Enemies

 * Bats
 * Goombas
 * Mines
 * Snoodles
 * Urchins
 * Gringills
 * Paragoombas
 * Boos

Green Stars
The Prima Games guide for Super Mario Galaxy 2 lists the Green Stars in reverse order.

Green Star 1
The player will redo the The Deep Shell Well mission. When they get to the columns area of Planet A, they should hear the jingling of the Green Star. The first Green Star is located behind one of the columns near the end of the area.
 * Enemies
 * Bats
 * Goombas
 * Mines
 * Urchins
 * Snoodles
 * Planets Visited
 * Under Ground Dangeon Planet A

Green Star 2
The player will redo the The Deep Shell Well mission again. When the player gets to the Launch Star, they should wait until it drops them. The player should be on a small ledge with a 1-Up Mushroom on the left side and the Green Star on the right side.
 * Enemies
 * Bats
 * Goombas
 * Mines
 * Urchins
 * Snoodles
 * Gringills
 * Planets Visited
 * Under Ground Dangeon Planet A

Music
The music for this galaxy was remixed for the World 2 theme in Puzzle & Dragons: Super Mario Bros. Edition.

Prima Official Game Guide description

 * "Grab a shell and dive into Slimy Spring Galaxy. This underwater course leads you through a garden of Snoodle, chambers full of Boos, and a pair of writhing Gringills. Don't worry. A beautiful sunrise awaits on the far side side of this watery world."

Trivia

 * If the player enters the Warp Pipe in the Starting Area of this galaxy, the music that plays in the bonus room is not the new bonus room music from Super Mario Galaxy 2, but rather the old bonus room music from Super Mario Galaxy. This also happens in secret areas in the Rightside Down Galaxy and the Upside Dizzy Galaxy, as well as in the second mission of the Slipsand Galaxy.
 * If Mario emerges into the treasure chest area, there will be no music playing, and an ambient sound plays instead. This is the second time this happens in the second game, the first being when Mario walks into the area before the big slide in the second mission of Tall Trunk Galaxy.