The invention relates to a method of inserting one or more cables into a cable-surrounding tubing (4) with the aid of a liquid (water). The specific gravity of the cable (3a) is adapted to correspond, or at least generally correspond to the specific gravity of the liquid (1a) used. The liquid (1a) present in the tubing and the flow of the liquid therethrough function as a means to support the cable (3a) and its cable section and/or to reduce the weight of the cable 3(a) and its cable section, and also as a means of entraining the cable and its cable section through the tubing (4). Each cable section (3a) to be laid in the tubing is intended to pass through a nozzle (10) or the like prior to entering the tubing through one end thereof. The insertion of one or more cables into the tubing is effected with the aid of a piston unit (20).