The invention relates to a swimming-pool cleaning apparatus which comprises: a body; at least one hydraulic circuit for circulating liquid between at least one liquid intake and at least one liquid outlet, and through a filtering device of the cleaning apparatus; a fluid-circulation pump installed in the hydraulic circuit downstream from the filtering device; means for adjusting the pressure inside the hydraulic circuit upstream from the circulation pump, in response to a detected variation of said pressure, said pressure-adjustment means comprising: at least one secondary liquid intake (21) connected to the hydraulic circuit, upstream from the circulation pump, said at least one secondary liquid intake (21) being provided with a valve (22) mounted rotatably movable about an axis of rotation, and with means for driving the valve from an open position to a closed position, said means for driving the valve comprising a float (26), the orientation and/or the force of which depend on the orientation of the cleaning apparatus relative to a horizontal plane.