Manhole

Manholes are covered holes that are located in various places in Super Mario Sunshine. The majority are found in Delfino Plaza, while a few are located in Ricco Harbor. Manholes lead to the intricate underground sewer system, and can lead Mario to places he cannot access aboveground, as well as to coins and other items. To access it, Mario must Ground Pound while over a manhole. The manhole covers, which have a sun on them originally, flip when Ground Pounded, revealing a moon. When underground, a remix of the underground theme from Super Mario Bros. plays. To get out of a manhole, Mario must jump below a manhole cover.

In other games, they are used by Rocky Wrenches as shelter. They can also be found in World 2-3 of New Super Mario Bros.

Manhole covers can also be seen in the Delfino Plaza stage in Super Smash Bros. Brawl but they serve no purpose.

Manholes also appear in Super Mario Odyssey. Mario can capture them to move them, allowing him to fall through the entrance the manhole in question was blocking.

Trivia

 * Although Manholes are not seen in Noki Bay, the underground theme is also played when Mario walks through hidden tunnels inside the cliffs.