A method for progressively producing an underwater laying-out channel (3) for an object (53) to be laid out, like a cable or the like, in an underwater ground by flushing and by mechanically loosening ground formations (7) which are resistive against flushing, by means of a mechanical loosening device (31) having a given maximum working depth, characterized by lowering the mechanical loosening device (31) to the ground formation (7) which is resistive against flushing, and advancing, in an advancing direction, the mechanical loosening device through the ground formation which is resistive against flushing, with the working depth being effective from the surface of that ground formation.