A pond device (1) comprising a fluid reservoir (6), at least two opposing first side walls (2) and at least two opposing second side walls (3), a special feature being that the pond device can be moved between a collapsed position, in which the first side walls face one another, and an unfolded position, in which the first side walls face away from each other, wherein the first and the second side walls are pivotally interconnected along edges (4) thereof, and wherein the first side walls and the second side walls jointly define the fluid reservoir (6) in the unfolded position.
