When Mario enters the level he will start out floating in a medium sized, submerged room featuring large windows and some small platforms.
While swimming around in this room, Mario won't be able to resurface to breathe, so the only way not to drown will be by collecting the red coins in a timely fashion. Mario can also collect regular coins from the rings to restore his breath.
Once all red coins have been collected, Mario can collect the power star to leave this level and there will be no need to return to this secret level ever again.
Inside the Jolly Roger Bay room Edit
The Secret Aquarium Edit
- Internally, this level is referred to as the "Secret Aquarium"
- If the player enters this level ingame, though, there will be no star select screen or title
- After collecting this level's red coins star, Mario will simply receive the regular "You collected a secret star of the castle"-message