The Deep Shell Well
The player starts in a cave, there is a pipe on the left of the entrance to the slide. The pipe brings you to a room with 3 shells and nine treasure chests. Sliding down the hole brings you to a tunnel which leads to a shell with a Bill Board next to it explaining that you can spin to grab a shell. You swim through a Snoodle and mine infested cave (a small tunnel is at the bottom left leading to the Comet Medal.) You go up a tunnel with urchins sliding down it then you break a wall made of bricks and 2 Gringills are chomping up to the wall. 3 Snoodles guard the path to the Launch Star which brings the player to a Boo infested galaxy. If you don't immediatly use the Launch Star, Mario will drop to a hidden section with a 1-Up. The new section starts with a Paragoomba flying above a tower-like structure which, upon jumping in from the top, goes deep down into Boo infested waters with a lot of walls with holes, there is a 1-UP that the Paragoomba is guarding. After swimming through the Boo infested tunnel you find a treasure chest with Captain Toad inside, who will give you a Power Star if rescued.
The Chimp's Coin Challenge
This star is basically the same thing as The Deep Shell Well but The Chimp gives you a minigame with a Highshore of 10000. Defeating enemies and collecting Coins grants you points. Beat his score and you get the star. The Comet Medal is replaced with a 1-UP and the walls aren't seen in the Boo infested section.