Noki Bay is one of the areas of Isle Delfino, the main setting of Super Mario Sunshine. Noki Bay is located at the north behind the island's "dorsal fin". The Nokis live here in the platforms floating in the bay. It's the only location on Isle Delfino that doesn't have an Italian translation. It's also the only 'world-type' location in the game not to feature Yoshi.
The structures have shells on them, possibly because the Nokis carry shells on their backs. Many small square pictures on the cliffs can be pushed in when sprayed, revealing a secret alcove. They are actually switches hiding several hidden tunnels and Blue Coins. The picture switches have six different designs on them, the blank ones making the total number of designs seven.
An old Noki fisherman and his grandson will help Mario throughout the levels, giving him a diving helmet and tips. Gooper Blooper makes a return here at one of the cliffs peaks. He blocks a hole to a room for the ancient Noki King's tomb. Several Noki shells are on the walls, as are two large jugs that hold a Blue Coin each.
Noki Bay is one of the most beautiful locations on the island, with crystal clear water and mysterious, old ruins. It is here that Eely-Mouth's gingivitis has polluted the waters. The eel is in a huge underwater city that can be reached by the large waterfall. There, Mario can clean the eel's mouth and collect red coins in the relaxing and peaceful surrounding of the underwater Noki City.
Mario must collect at least twenty Shine Sprites to unlock this area. Noki Bay is entered from Delfino Plaza by heading to the pier near the Shine Gate and staring up at the sun inside a column of light, a likely reference to the method of accessing the Tower of the Wing Cap in Super Mario 64.
Episode 1: Uncork the Waterfall
The misson starts out when Mario lands on a platform amidst a purple, polluted Noki Bay. He then meets the Noki Elder, who explains that someone has corked the waterfall, which he believes to be the cause of the pollution. Mario must traverse the platforms to reach the top of the cliff and avoid the Goop and Glorpedos in his path. He can use F.L.U.D.D. to spray the Goop off the walls to reveal more platforms in order to proceed.
Upon reaching the top near the corked Waterfall, is a Monty Mole inside a cannon, who throws Bob-ombs at Mario. Mario must stun the Bob-ombs with water then throw them back at Monty Mole three times to defeat him. The pressure of the waterfall then throws the cork and the cannon with the Monty Mole into the sky. The waterfall is then restored to the bay and Shine Sprite appears for Mario to collect.
Episode 2: The Boss of Tricky Ruins
Gooper Blooper makes a return appearance here. Mario has to find his way into the ancient Noki King's tomb where the Shine Sprite is. To do so, Mario must shoot blocks with water to form paths that he can walk through. Mario must make his way to the top of the cliff using the pathways. The Rocket Nozzle is present in this level, but the player must use the paths he used on the first level of the Noki Bay and find a secret pathway leading off the path to the waterfall. The Rocket Nozzle is a very useful item in this level, as for it can help Mario get higher without using the paths. At the top, Mario must battle Gooper Blooper. It attacks the same way he did in Ricco Harbor. After Gooper Blooper is defeated, Mario can go through the hole he was sitting on, and collect the Shine Sprite.
The Noki fisherman has figured out what's polluting the bay, but he makes Mario practice diving deep under the surface by telling him to collect eight Red Coins in a bottle full of water.
Episode 4: Eely-Mouth's Dentist
At the beginning of the stage, the Noki Elder's grandson states that his grandfather is waiting at the top of the cliffs. There, the elder explains that a giant eel at the sea floor is the cause of the water pollution; specifically, its rotting, cavity-filled teeth. He also states that the waterfall created a gap that can be used to enter the Noki's home. At the floor, Mario must clean the teeth of Eely-Mouth using F.L.U.D.D.. Doing so causes the eel to leave and a Shine Sprite to appear. Additionally, the water does not appear polluted for the next missions.
Episode 5: Il Piantissimo's Surf Swim
Episode 6: The Shell's Secret
Mario starts out in a rectangular glass box. Mario must wall jump to exit the box. Then, he must jump on a green rotating platform and land on a yellow platform. After crossing several platforms that move in and out, he climbs up a pole. Now, he must jump on a rope, and use his wall-jumping skills to access several rotating platforms. Mario will then go to the top of several connected spinning platforms placed on top of each other, go up another rotating platform, and land on a red platform that has the Shine Sprite on it.
Episode 7: Hold It, Shadow Mario!
This episode is the Shadow Mario episode for Noki Bay. It must be completed in order to access Corona Mountain and fight Bowser and Bowser Jr.. In this episode, Mario must chase down Shadow Mario, as always, and squirt him with water until he gives up a Shine Sprite.
Episode 8: The Red Coin Fish
Mario needs to dive down to the bottom of the sea to claim the Nokis' gift for him: a group of Coins and Red Coins swimming in the shape of a fish, which is named the Red Coin Fish. Mario must collect the eight Red Coins in the body of the fish in order to make a Shine Sprite appear. Every so often, the Coins and Red Coins comprising the fish's body will explode outward for several seconds, making it more difficult to collect the Red Coins.
Episode 9: A Golden Bird
Mario must navigate to the area that he went to in Episode 2. He must walk forward to a hole in the wall, go inside, and Wall Jump upward. He will find a hole in the left side that he can enter. Mario must walk through this hole to a crevice in the side of the cliff. There will be another hole that he must enter, which automatically propels Mario up to the top of the cliff. Mario will find a tree and a Yellow Bird flying around the top of the cliff. Mario must spray this bird multiple times with water from F.L.U.D.D.. When the bird is sprayed enough times, it will turn into a hidden Shine Sprite that Mario must collect. 
Episode 10: Red Coins on the Half Shell
In this episode, Mario must replay Episode 6, though this time he must enter the Shell's Secret and collect eight Red Coins. If he manages to collect them all before the 1:30 time limit is up, a Shine Sprite will be revealed.
Blue Coin Locations
NOTE: Blue Coins cannot be obtained during Episode 3.
Steep cliffs and sea beds are what the Nokis call home. The huge waterfall and three soaring towers resonate with mystic history.
The theme heard in Noki Bay is performed by a wide variety of different flutes (such as the Western flute and panflute, among others). They are accompanied by harp, xylophones, and various other percussion instruments. It was composed by Shinobu Tanaka.
Names in other languages