Page 3, Super Mario Sunshine Cheats for GameCube
Once you have unlocked the level "Noki Bay", go to any episode and go to where there is already a wall for you to wall jump in. Get to the top of the wall and get into the tunnel. Proceed to the end of the tunnel and you will end up on the side of a giant cliff. You will see and opening. Go into the opening and you will automatically jump up through the cliff. Do not press anything during this time. You will end up on top of the cliff and you will see a yellow bird next to a tree. Jump on top of the tree and with the Squirt Nozzle, douse the yellow bird three times (or more if you are not quick enough) and for your effort, the yellow bird will transform into a Shine Sprite and land on the same cliff you are on. That particular Shine Sprite is on of the three secret and hard to get Shine Sprites that you really want to get out of the way. Once you get the Shine Sprite, you will be one Shine Sprite closer to completing the game!
Contrary to popular belief, defeating Bowser is not required to re-access the airstrip.
All you need is access to Corona Mountain. Once there, pause and hit "Exit Level".
And voila! The flood will vanish, and the ferry to the airstrip will run...and you didn't even beat Corona Mountain.
Secret Sunshrine: Go behind the lighthouse(entrance to the beach) and jump on the platforms using fludd. On the last platform, there should be a warp pipe.
Jump in it and there will be some kind of small game. Dodge the holes, and at the end, balance on a thin plank and go to the shrine.
If you fall off, you will not only have to start over, but you will lose a life.