Named for the algae that give it its perpetual colour, Green Lake is a body of water between the Western Ithmia and Siroccian Mountains, just south of the Prelatorian Highway. It was formed long ago by a small meteor that collided with the continent of Sapience. The depression filled with water, which in turn filled with abundant weeds and algae. Prolonged exposure to the stagnant water has left the surrounding wildlife warped and mutated, and the scummy water itself is unsafe for drinking by those not accustomed to it.
The squire named Jamison often stops off here to water his steed, and the Kastalian priest known as Marat may sometimes be seen puttering about the shallow mountain slopes nearby. Bears, toads, mud eels, giant mosquitos, red foxes, pythons, freshwater clams, pelicans, and catfish make this place their home, and it is also rumoured that the feared and mysterious beast known as the skolef lairs somewhere in this area. The hunter Garian once frequented this area, but in light of his increasing years he has since retired to the Crystal Leaf Inn where he pays for any furred trophies that might be bagged along the lake's edge.