a large distance that is larger than the cross section of the object depending on the embodiment of the underwater sound damper the side edges that are movable relative to one another are part of a single support structure for example and or of separate support structures which are formed for example by a row of a plurality of parallel vertical cables and or net strips and or netting tubes that are provided with sound reducing elements and are retained on a floor element at the lower end and can float freely at the upper end a net is preferably used as the support structure for the sound reducing elements alternatively to a net it is also possible to use a grating a cage in particular a narrow cage a wire mat a perforated sheet plate or a rigid wire mesh a plurality of the rigid support structures formed as surface bodies are movable relative to one another between the idle position and the working position preferably in a translational and or rotary manner in this case the support structures are preferably arranged relative to one another in graduated planes or in concentric rings support structures in the form of cages can also be telescopic or can be arranged on and or next to one another for example in stacks it has proven advantageous that the upper end and the lower end of the at least one support structure are movable in.