The invention relates to a method for ground-working at a bottom of a body of water and a cleaning device for cleaning an underwater ground-working apparatus. The cleaning device has an enclosing body which extends substantially from a bottom of a body of water to above the water surface and enclosing an inner space, along which the ground-working apparatus can be moved, and a separating device, through which in the enclosing body an upper portion of the inner space can be separated off to form a cleaning area, in which the ground-working apparatus can be received and soil and contamination cleaned from it.