Wario Land 3: Part 20: The Stagnant Swamp (Gray Chest)

To make it clear that this is indeed a swampy level, the water here is too murky for Wario to even swim and dive in. Instead, start off by having Wario go underground, as the Gray Key is found down here. Then eventually go back to the surface and rely on the pulleys above you. Let them eventually guide you to a pulley that moves down‑right. Grabbing this will have it slide down fast, leading Wario into a roll strong enough to break through the log that's guarding the Gray Chest. The Stagnant Swamp's Gray Chest Treasure is a Flute! So then Wario played an exotic tune from the Flute, causing snakes to appear out from jars in The Grasslands, The Volcano's Base, and The Peaceful Village. Stuff like this just reinforces that this game is a semi‑or segmented Metroidvania. Even if you don't always get powerups as rewards, you're still finding items that unlock new routes to old levels.