Super Mario 64/Dire, Dire Docks

Dire, Dire Docks is the ninth stage in Super Mario 64 DS. 30 stars are required to access it. It is found in the room with the Bowser in the Lava Sea stage, but the portal is blocking the Bowser stage. This area is known as Dire, Dire Docks. After you clear the first level of it, the portal will move to the back of the room.

Star 4: Through the Jet Stream
To get this star, go to the second section of the course, then grab the Wario cap if you are not Wario. Surface, then hit the ? Block. Sink underwater to the area making rings. Stand there until 5 go around you to earn the star.