In the Pacific the American Navy managed to do what the German Kriegsmarine had failed to do in the Atlantic. The systematic attack of shipping in and around Japanese home waters denied them access to vital war resources, particularly oil, from their overseas empire.
The Gato class of Submarine was designed to operate in the Pacific with the fast Carrier fleets. It was much bigger than a German U-Boat and had a huge range, being able to remain on patrol for over two months at a time. Early operations were frustrated by problems with torpedoes, but by 1941 these had been sorted out and the Gato, and its derivatives the Balao and Tench classes, went on to become very effective, sinking a vast amount of Japanese shipping.