On 21 December, in the approach to Bungo Suido (Bungo Channel), "Sailfish" intercepted six large freighters escorted by three destroyers. With five torpedoes left, she fired a spread of three stern tubes, scoring two hits on the largest target. Diving to escape the approaching destroyers, the submarine detected breaking-up noises as "Uyo Maru" () went to the bottom; destroyers counterattacked with 31 depth charges, "some very close". "Sailfish" terminated her tenth patrol at Pearl Harbor on 5 January 1944. She claimed three ships for , plus damage to one for , believed to be the most successful patrol by tonnage to date; postwar, it was reduced to two ships and (less "Uyo Maru") .