 In 1953, he transferred to the ocean survey ship USC&GS "Pathfinder" (OSS 30), conducting hydrographic surveys in the western Aleutian Islands, Bering Sea, and Cook Inlet.By the end of 1953 he was "Pathfinder"'s operations officer.In 1954, Nygren left "Pathfinder" for over three years of duty as head of a Coast and Geodetic Survey Division of Geodesy field party measuring the acceleration of gravity.