Apparatus for adjusting a media pressure with respect to an ambient pressure which is defined, when using the apparatus, by a depth-dependent seawater pressure, wherein the seawater pressure acts on a compensator device, which allows a reversible change in length or elongation, wherein at least two compensator elements of the compensator device are provided in sequence in the direction of the change in length or elongation, wherein, in the application, at least one end wall on the end face of a pressure intensifying device is exposed to the effect of seawater, wherein the pressure intensifying device comprises a double piston arrangement, which, with its one piston forming the end wall on the end face, is adjacent to a seawater chamber and, with its other piston, is adjacent to a media chamber, wherein the double piston arrangement is guided such that it can move axially in a receiving housing, wherein an inner wall of the receiving housing forms a running surface for the pistons (21, 27), wherein the appliance comprises a cylinder, which forms the receiving housing, wherein the compensator device is provided on the inside of the receiving housing between the piston on the seawater chamber side and an entrance point to the cylinder, and wherein the end wall on the end face is set back with respect to the entrance point for seawater in the direction of the pressure intensifying device, wherein the compensator device is formed by a bellows; wherein the compensator elements formed by individual bellows pleats arranged in succession, which at least partially form the wall of the bellows; wherein the bellows is welded at its free end to the cylinder in the region of the entrance point; and wherein, during operation with preloading, the other end of the bellows is loosely in contact with the outer circumferential edge of the adjacent end face of the piston on the seawater chamber side. wherein, in the application, at least one end wall on the end face of a pressure intensifying device is exposed to the effect of seawater, wherein the pressure intensifying device comprises a double piston arrangement, which, with its one piston forming the end wall on the end face, is adjacent to a seawater chamber and, with its other piston, is adjacent to a media chamber, wherein the double piston arrangement is guided such that it can move axially in a receiving housing, wherein an inner wall of the receiving housing forms a running surface for the pistons (21, 27), wherein the appliance comprises a cylinder, which forms the receiving housing, wherein the compensator device is provided on the inside of the receiving housing between the piston on the seawater chamber side and an entrance point to the cylinder, and wherein the end wall on the end face is set back with respect to the entrance point for seawater in the direction of the pressure intensifying device, wherein the compensator device is formed by a bellows; wherein the compensator elements formed by individual bellows pleats arranged in succession, which at least partially form the wall of the bellows; wherein the bellows is welded at its free end to the cylinder in the region of the entrance point; and wherein, during operation with preloading, the other end of the bellows is loosely in contact with the outer circumferential edge of the adjacent end face of the piston on the seawater chamber side.