Slimy water

Slimy water, also known as purple pollutant or purple goo, is a form of goop-polluted water that appears in Super Mario Sunshine. While Mario is floating on its surface, one section of his Health Meter is depleted about once every two seconds. It harms him only while he is on the surface of the water, though he slowly loses air as usual while underwater. Unlike with many kinds of goop, Mario cannot clean it with FLUDD.

Slimy water appears in three areas in the game: Episode 6 of Bianco Hills (The Secret of the Dirty Lake), Episode 1 (Gooper Blooper Breaks Out) through Episode 5 (Gooper Blooper Returns) of Ricco Harbor, and Episode 1 (Uncork the Waterfall) to Episode 4 (Eely-Mouth's Dentist) of Noki Bay. The color and type of slimy water vary with the level in which it is encountered. In Bianco Hills, brown and light-green goop covers the surface of the lake around the Big Windmill, having spilled out from the Cliff Spring Cave prior to The Secret of the Dirty Lake. Ricco Harbor's slimy water, also classified as oil, comes from large quantities of spilled black goop that cover the surface of clean water in several areas. Noki Bay's translucent purple slimy water came about as a result of Eely-Mouth's gingivitis.

Slimy water bears a strong resemblance to poison, which appears in the Lily Pad Ride level in Super Mario Sunshine as well as in many other games. However, slimy water is less harmful compared to poison, as it only deals gradual damage as opposed to instantly causing Mario to lose a life.