"Wahoo" was ready for sea again on 16 January 1943. She performed sonar tests in Moreton Bay with the destroyer before beginning her third war patrol. Three days later, the submarine passed into Vitiaz Strait "en route" to her patrol area. "Wahoo"s orders were to reconnoiter Wewak, a Japanese supply base on the north coast of New Guinea between Kairiru Island and Mushu Island. There was one large problem: "Wahoo" had no charts of the harbor. However, it turned out that Motor Machinist's Mate Dalton "Bird Dog" Keeter had bought a cheap school atlas while in Australia. It had a map of New Guinea with a small indentation labeled "Wewak". With that as a reference, a blowup of the Navy chart was made.