Goop is the substance covered by Shadow Mario in Super Mario Sunshine. It comes in several colors - Brown, Black, Magenta, Red, and Blue to be exact - and all except for blue, magenta, and red have a white paint mixed in (the aforementioned have yellow in it).
The effects of the goop vary as to the color of the goop. In the brown, goop and colorful goop if you stand in it for too long, you'll lose one unit of energy. The fire goop will burn you on contact, and the electric goop will electrocute the player on contact. Each goop can be removed via use of F.L.U.D.D.
Types and Areas Found
There Is Oily Goop, Brown Goop, Colorful Goop, Firey Goop, and Electrical Goop. Brown Goop is found in Delfino Plaza and Bianco Hills. Oily Goop is found in Ricco Harbor, Noki Bay, and Delfino Plaza. Colorful Goop is found at Delfino Airstrip and Noki Bay. Fire Goop is mainly seen at Pianta Village. Sirena Beach has Electrical Goop.