Unalaska, Alaska
A unit of Submarine Division 41 (SubDiv 41), "S-18" moved north in mid-January 1942. Into March 1942, she conducted defensive patrols out of the new and still incomplete submarine base at Dutch Harbor on Amaknak Island in Unalaska, Alaska. In mid-March 1942, she got underway for San Diego, California, underwent repairs there until mid-May 1942, and then returned to the Aleutians.