Pollution

Pollution is a very dangerous hazard and the main focus in Super Mario Sunshine. It was caused by Bowser Jr. posing as Shadow Mario using his Magic Paintbrush to pollute the entire area of Isle Delfino. He did this to frame Mario and easily kidnap Peach according to the policeman, all of the pollution was washed away after the massive flood.

Effects
Pollution has the ability to sink large structures and even citizens of Isle Defino. Also, if Mario stands in the pollution for too long, then he will start slowly lose HP. Mario can wash away the pollution using FLUDD. There is actually different types of pollution:
 * Regular: The most common goop. It is usually brown, orange, and black in color.
 * Fire: Goop that only appears in Pianta Village. Mario gets burned if he touches this goop.
 * Electric: Goop that only appears in Serina Beach. It is yellow and green in color and must be sprayed or avoided.

Locations and Descriptions
Pollution varies in colors and effects:

Isle Delfino
On Isle Defino, the pollution is mainly black in color. Pollution also blocks the way to Bianco Hills, Gelato Beach, and Ricco Harbor. Mario must fight the Polluted Piranha Plant in order to clean up the goop. Pollution can also be found on the Shine Gate and the two Bells on the plaza. Mario must have the Rocket Nozzle in order to reach them and spray them. After Mario does so, he is awarded with Shine Sprites.

Bianco Hills

Pollution is nainly caused by more Polluted Piranha Plants and Petey Piranha in this level. There is also a polluted lake that leads to a secret. Mario must be careful of the water as he quickly loses HP the more he stays in the water. Pollution here is mainly brown in color.

Ricco Harbor
Pollution is mainly caused by Bloopers and Gooper Blooper in this level. There is also polluted lakes in two missions that act the same as the one from Bianco Hills. Pollution is mainly black in color. Ricco Harbor is known for being one of the most polluted areas in Isle Delfino.

Pinna Park
Pollution is found very little in Pinna Park only on the beach. It is caused by enemies that try to drop on Mario and harm him.

Sirena Beach
Pollution is mostly found in the first mission which was caused by the manta. It only appears as the dangerous blue-yellow electric goop.

Noki Bay
Pollution is found both on land and in the water of this level. It is caused by the mole, Gooper Blooper, Eely Mouth. Mario can defeat all of them to make Noki Bay peaceful again.

Pianta Village
Only the fire Pollution appears in this level. Mario, for the most part, cannot spray away the goop and must make his way around it. The Fire Pollution is mainly caused by fire Chain Chomps and Shadow Mario.

Trivia

 * Gelato Beach and Corona Mountain are the only areas that doesn't contain any Pollution.