Whirlpool

A whirlpool is a spinning column of water that appears in some Mario games. Usually, its purpose is to suck the player down into it, causing damage or even making them lose a life.

Super Mario RPG: Legend of the Seven Stars
In Super Mario RPG: Legend of the Seven Stars, whirlpools appear in almost every underwater area. When Mario is sucked by one, he is taken to the bottom of the water, where the player can reach other areas. This is because Mario cannot dive underwater on his own. However, Mario cannot resurface by touching a whirlpool.

Super Mario 64 / Super Mario 64 DS
A whirlpool appears in Super Mario 64 and its remake in Dire, Dire Docks. It appears in the middle of the first area, and if Mario, Yoshi, Luigi, or Wario goes near it, he is possibly sucked in and defeated instantly.

New Super Mario Bros.
In New Super Mario Bros., whirlpools appear only in World 6-5. If Mario gets trapped in one, the player must repeatedly press to avoid being sucked down, or else they lose a life. After a while, the whirlpool disappears, and Mario can pass by. However, one whirlpool allows Mario to access the level's third Star Coin.

Super Mario Galaxy
In Super Mario Galaxy, whirlpools appear in the Sea Slide Galaxy and the Bigmouth Galaxy. They are thin and have a dark blue color. They do not suck Mario but push him.

New Super Mario Bros. 2
Whirlpools reappear in New Super Mario Bros. 2, acting the same as they did in New Super Mario Bros. They appear only in World 3-2.

Mario Party
Whirlpools appear in Mario Party in Yoshi's Tropical Island, blocking a Pink Yoshi on the middle island.