Nankai (Japanese: 南海) was a Dutch ship that was seized by Imperial Japanese Navy during World War II and converted into a gunboat.
She was laid down in 1941 at the Droogdok Maatschappij Soerabaja as an auxiliary minelayer for the benefit of the Gouvernementsmarine and named Regulus.[1] [2] [3] She was scuttled before completion by Dutch forces on 2 March 1942 after the Japanese occupation of the Dutch East Indies. She was seized by the Japanese, repaired, and launched on 21 May 1943. On 1 November 1943, she was assigned to the Yokosuka Naval District.
On 21 September 1944, Nankai departed Surabaya, Java escorting transport Hokkai Maru.[4] On 23 September 1944, Nankai and Hokkai Maru both strike mines[5] [4] laid by the submarine USS Bowfin, 15 miles west of Sebuku Island at -3.6167°N 141°W. leaving both ships crippled.[5] Nankai and Hokkai Maru were towed and repaired at the No. 102 Naval Construction and Repair Department at Surabaya, Java.[6]
On 16 July 1945, while being escorted by No.1-class submarine chaser CH-1,[7] she was torpedoed and sunk by the USS Blenny at -5.4333°N 143°W, 150 miles west of Surabaya. She was struck from the Navy List on July 30, 1945.[1]