 
Eely Mouth is a giant eel who lives deep in the underwater depths of Noki Bay. During Mario's sub-quest to purify the polluted water in the beatiful bay, in one part he has to dive underwater to Eely Mouth's underwater lair. He will possibly hurt Mario, but this is due to his eight teeth, covered with horrible gingivitis. Then Mario must use FLUDD's water jets to clean Eeely Mouth's teeth. Four become clean, Three become rotten a come out of his mouth, And one is golden. After Mario cleans all of Eely Mouth's teeth, FLUDD gives a good moral for young (and elderly alike): "Remember to take proper care of your teeth!" Eely Mouth then goes away, somewhere unknown, but leaving 20 Golden Coins, and his Golden tooth, which turns into a Shine Sprite. This is Mario's reward for the "dental" work he has done. It is has to determine whether Eely Mouth is a "he" or a "she"; or even a boss.