Barnacle Bay is an area in Super Mario Sunshine 2: Islands of Darkness. A small bay full of life and bloopers, Barnacle Bay can be accessed from the Lighthouse in Isle Claw.
- Goop Drain Out: In this mission, black oily goop is coming from a hidden tunnel on the edge of the bay. Mario must enter using the logs near it. Once inside, if he sprays off all the goop on the platform in 30 seconds he'll get a Shine Sprite.
- Secret of the Steamboat: In this mission, the characters have to jump into the Smokestack to play a secret level.
- Fishy Fight: In this mission, the steamboat has been overtaken by a giant Cheep-Cheep made of goop named Fishy. Mario must defeat the foe to get the Shine Sprite.