An exemplary embodiment of the jet hammer includes an outer sleeve, impact assembly, and a valve assembly. The impact assembly is positioned in sliding relation to the outer sleeve to provide the impact of the jet hammer. The valve assembly generally comprises a cap screw, adjustment sleeve, valve port, inner compression spring, outer compression spring, and lock nut. The inner compression spring is relatively less compressible than the outer compression spring. In operation, fluid enters the valve assembly and acts on the compression springs forming an operational seal between the valve assembly and the impact assembly. In response, the outer sleeve is slidingly displaced from the impact assembly thereby compressing a main compression spring positioned along the mandrel shaft. Once the pressure acting on the valve assembly is released, the main compression spring decompresses forcefully causing the outer sleeve to impact a connection port, bit, tool, or other member attached to the upper end of the mandrel. This impact is translated onto the obstruction or item to be struck. The impact assembly may also be capable of rotational movement with respect to the outer sleeve wherein the mandrel shaft may contain at least one rotation nozzle thereon. The rotation nozzles allow for fluid communication from the mandrel's internal bore, through the nozzles, and against the proximate inner wall of the outer sleeve. This interaction causes the mandrel, and by connection the connection port, bit, tubing, or tool attached thereto, to rotate during the downward stroke of the hammer. Rotation nozzles may be located on the connection port and/or bit for additional rotational force.