Mario and Luigi go inside the Dire, Dire Docks course. Mario pulls Luigi by the leg and makes him go underwater. They stay underwater for a bit, and look around. Mario sees a tunnel and motions Luigi to go in. Luigi nods and Mario speeds off ahead of him. Luigi chases him but gets caught in the whirlpool's current. He swims frantically to get away. Meanwhile Mario is inside the tunnel and continuing. He quickly looks back and has a glimpse of Luigi swimming frantically for life. Mario swiftly changes course and goes to save Luigi. Just when Mario is about to get out of the tunnel, Luigi frees himself from the whirlpool's current and motions for Mario to not come. Mario goes back inside the tunnel and Luigi begins swimming after him. Suddenly Luigi feels he can't hold his breath any longer. He frantically swims after Mario and accidentally passes inside a blue circle a Manta Ray that passed by left. Magically, he recovers oxygen as a number 1 goes up above him and disappears.
Luigi: (Hmm, that's weird. I'll try to pass by another of his rings again.)
Luigi chases the Manta Ray and as he passes inside another ring he recovers oxygen again as a number 2 goes up above him.
Luigi: (Cool!)
Luigi continues chasing the manta ray and passing inside the rings it leaves behind and doesn't notice Mario inside the tunnel grabbing his own throat and flailing his arms wildly. Just when Luigi passes inside a ring the fifth time, a Star appears out of the manta ray and takes a position atop the whirlpool. Luigi sees Mario going down and thinks quickly. He swims fast and manages to get the Star.
Luigi (underwater): Here we g- GLUB GLUB!!!
Mario and Luigi are immediately transported back to the castle.
Mario: *cough* to the *COUGH* Star.