Abstract: The present invention relates to a device intended to create a motion in a liquid, in particular at the surface thereof, this liquid being contained within a tank defined by one or more walls, in particular in a swimming pool, this device comprising an element in contact with the liquid in which, in particular at the surface of which, a motion is to be created. The device according to the invention comprises, as an element, a floating or submerged assembly which is not solidly fixed to a wall of the tank, the said assembly comprising two bodies (1,5) mutually connected by at least one means (7), this means (7) being intended to move the bodies (1,5) relative to one another in a manner such as to create a motion in the liquid, in particular at the surface thereof.