of coal from Mombasa in British East Africa to Aden. Two torpedoes hit Storviken on her starboard side, and she sank by the stern at . I-10 took two members of her crew prisoner. At around 16:10 on 4 October 1943, I-10 detected the sound of multiple propellers while submerged in the Gulf of Aden, and soon sighted Convoy AP-47, consisting nine merchant ships bound from Aden to Abadan escorted by two destroyers. I-10 pursued the convoy, surfacing after sunset. When northwest of Cape Guardafui, the northernmost tip of British Somaliland, at 05;10 on 5 October, she fired three torpedoes at overlapping targets at a range of , then dived to . One torpedo struck the 9,057-gross register ton Norwegian armed tanker on her starboard bow at . As major flooding progressed, her master ordered her crew to abandon ship, but the crew returned to Anna Knudsen when the flooding abated. I-10′s crew, meanwhile, reported hearing three loud explosions followed by breaking-up noises indicating the sinking of one or more ships, and claimed three merchant ships sunk. I-10 suffered minor damage to her engine room during a brief depth-charging by the convoy′s escorts. In the Indian Ocean near Addu Atoll on 24 October 1943 at 11:25, I-10 fired two torpedoes at the British 4,533-gross register ton armed motor vessel , which was on a voyage from Calcutta in British India to Durban, South Africa, carrying 8,700 tons of general cargo. Both torpedoes missed, so I-10 surfaced and opened gunfire, starting a fire aboard Congella. Congella′s crew abandoned ship, and she sank at . I-10 took her radio operator prisoner. The British whaling ship Okapi and two Royal Air Force Catalina flying boats rescued her other 37 survivors. Three gunners and 25 crew died in her sinking. I-10 concluded her patrol with her return to Penang on 30 October 1943. November 1943–February 1944 I-10 departed Penang on 5 November 1943, called at Singapore from 7 November to 7 December 1943, and then proceeded to Sasebo, which she reached on 16 December 1943. She underwent repairs and an overhaul at Sasebo, during which she was attached directly to 6th Fleet headquarters on 1 January 1944. When her repairs were complete, I-10 departed Sasebo on 3 February 1944 bound for Truk. On 9 February 1944, Fleet Radio Unit, Melbourne (FRUMEL), an Allied signals intelligence unit in Melbourne, Australia, decrypted a Japanese message reporting