Soap Bubble
From the Super Mario Wiki
Soap Bubbles are Bubbles released by the Hippo of Super Mario Land 2: Six Golden Coins. When the Soap Bubbles are released, Mario can go inside the bubble and "swim" in the sky. These bubbles only appear in the Hippo Zone, the home of the bubble-spitting Hippo.
[edit] Trivia
- By execution of a certain glitch (more specifically the pressing of the start button on the exact instant Mario touches a Soap Bubble), Soap Bubbles (albeit made up of strange symbols) can be used in any stage.

