After refueling at Midway, she was alerted by ULTRA of a fast convoy of Japanese ships before she arrived on station. About southeast of Yokosuka, on the night of 3 December, she made radar contact at . The group consisted of the Japanese aircraft carrier , a cruiser, and two destroyers. Despite high seas whipped up by typhoon winds, "Sailfish" maneuvered into firing position shortly after midnight on 3–4 December, dived to radar depth (just the radar aerial exposed), and fired four bow torpedoes at the carrier, at a range of , scoring two hits. She went deep to escape the escorting destroyers, which dropped 21 depth charges (only two close), reloaded, and at 02:00, surfaced to resume the pursuit. She found a mass of radar contacts, and a slow-moving target, impossible to identify in the miserable visibility. As dawn neared, she fired another spread of three bow "fish" from , scoring two more hits on the stricken carrier. Diving to elude the Japanese counter-attack, which was hampered by the raging seas, "Sailfish" came to periscope depth, and at 07:58 saw the carrier lying dead in the water, listing to port and down by the stern. Preparations to abandon ship were in progress.