On top of having to survive this raft ride over poison in the dark, Boos, Big Boos, and Peepas infest these Poison Bog. You need the Beam Box at the level start to help deal with the ghosts.
Green Star #1
The raft passes under a set of chain-link fences early on, and at the top of them is a Green Star. You can easily reach it by climbing the fences with a Cat Power-Up. If this isn’t an option, you’ll have to use a ? Block to reach an invisible platform that helps you get on top of the fences and reach the star.
After collecting the Green Star, you can avoid the enemies close to the water by staying up high on the fences. You eventually reach a large wooden platform with a swarm of Boos waiting for you.
Green Star #2
The second Green Star hangs seemingly out of reach over the poisoned water. However, the rafts pass by a bridge of invisible platforms that take you straight to the star.
Green Star #3
The raft abruptly slides downwards, into the waiting maws of three Big Boos. Wipe ’em out with the Beam Box, then avoid the Warp Box for the moment and jump onto the Beam Boxes behind it. You can then wall jump off the wall and reach the Green Star.
The Goal Pole zone has a set of invisible platforms you can use to get a better chance at topping the pole.