Eely-Mouth

Eely-Mouth is an eel only appearing in Super Mario Sunshine. It lives in the Nokis' ancestral home, a massive underwater chamber below Noki Bay, and its is the cause of the widespread pollution in the area. In order to purify Noki Bay's water, Mario must clean Eely-Mouth's eight teeth, three of which are rotten and fall out after being sprayed with FLUDD's water. One of its teeth is revealed to be golden once it is cleaned off. Eely-Mouth has two separate pairs of eyes on either side of its mouth; one pair appears to have a masculine appearance, and the other feminine.

At the start of the episode, the Noki elder explains to Mario that he has finally figured out the problem as to why the bay is polluted, and sends him to the ocean floor to fight the giant eel. Due to its intense suffering, Eely-Mouth is aggressive and spins around very fast, and then rise upward and open its mouth. This is when Mario can attempt to clean its teeth, by spraying them with FLUDD. After some time, Eely-Mouth sucks in water, and Mario as well, if he is too close. If this happens, Mario is quickly spat back out and loses air. Due to Eely-Mouth's intense pain, toxic, purple tears regularly come out of its eyes. These tears damage Mario if touched, but refill his breath meter. If Mario sprays the bubbles with water from FLUDD, they pop into a cluster of smaller regular bubbles that do not harm Mario and replenish his air supply. Once all the teeth have been cleaned, Eely-Mouth retreats back into its cave, and spits out its golden tooth, which turns into a Shine Sprite which falls to the bottom, that Mario must collect. As the eel recedes into its cave, it also leaves behind twenty coins in a heart-shaped formation, which float just above the mouth of its cave (collecting them is optional), most likely as a sign of thanks. After Eely-Mouth has completely disappeared, FLUDD comments, "Remember to take proper care of your teeth!"

In Mario Golf: Toadstool Tour and Mario Golf: Advance Tour, the name "Eely-mouth" can appear on the leaderboard.