The Acid River is a river that Finn crossed in the episode "Another Way." It is a river that will burn someone, described by the Talking Bush as being "like orange juice," and also that "it's gross." The river is so acidic that it sunk a boat by dissolving its hull, as explained in the episode. It is also dangerous because of its swift current, as well as being infested with electric eels. The only way to pass it is by crossing the bridge above it, but it is a Trap Bridge and assumed to be lethal to use. The Shrub seems thoroughly convinced it is impossible to cross the river, explicitly stating so a number of times and calling Finn a "dummy" for thinking he can get across.