Have you seen the island that the guy was shipwrecked onto? If you do, then you should have seen the hot blob on the green tube. To get it out, you need the Yoshi that is on the rooftop of Delfino Plaza. Put Yoshi onto the three boats. Once you get to the island, use Yoshi's juice to spray the blob. It will disappear and you will be able to enter the tube.
A yoshi trick:
There is another way to get Yoshi fruit from trees. First, turn the grey control stick around as fast as you can. Then, press the "A" button. Finally, press the "R" button. Yoshi will spin in the air and spray all of the fruit off the tree.
How Yoshi can take care of himself:
Are there times when you want to leave Yoshi somewhere safe while you go somewhere else. Well, now you can. In Delfino PLaza, take Yoshi to a fruit stand or somewhere with fruit. Leave him there and he will eat fruit by himself. If you go through one of those colored portals and come back to Delfino Plaza, Yoshi will be back in his egg.
During the flood, go to noki bay entrence (DO NOT GO IN) Turn towards the fountain, you will see the stuff that is above the fruit stand. Go on the shorter one and face the taller one. Then fall thru the middle and imidiatly use the hover nozle and hover UNDERWATER. It will stop and you can breath underwater!
(supplied by: BenjaminGo25)
To get to Delfino Airstrip keep collecting shine sprites until the flood happens then enter Corona Mountian, if you lose the boat will be there, but if you win re-enter your game and the boat will also be there.
(supplied by: Golden Sun lover333)
How to kill bowser:
It's very easy. First go to corona mountain and pass it. You will see at the end of the level a red cloud. Jump through that cloud and you will find bowser. Then with the rocket nozzle use it,(in a rock with a sign kind of like a fire)and press L to do a very hard sit. Do this on all of the rock platforms and you will kill bowser. Note: Be carful when passing to another platform. Bowser might throw flames at you.
(supplied by: Kirby9021)
If you are in the water, you can spray water without running out.
If you want to use the hover wile you are in the water, jump and press R and steer. This is a very useful trick if you want to travel faster in the water.
To use the rocket while in the water, charge it up before it fires. Right before it fires, jump out of the water.
You can always use the turbo in water. Charge it up with R then release R. You can also dive in the water and use it but don't stay under too long or you'll run out of breath and die.
(supplied by: DragonHUL)