High Quality Content by WIKIPEDIA articles! Oryoku Maru was a Japanese passenger cargo ship. In World War II, Oryoku Maru was used as a troop transport and prisoners of war (POWs) transport ship (Hell ship). She left Manila on December 13, 1944, with 1620 POWs, mostly American, packed in the holds. 1900 Japanese civilians & military personnel occupied the cabins. As it neared the naval base at Olongapo in Subic Bay, US Navy planes from the USS Hornet attacked the unmarked ship causing it to sink on December 15. About 100 men died aboard the ship from suffocation or dehydration during the two nights aboard while nearly 200 others were killed in the bombing or shot in the water as they tried to escape.