Located  between alava pier and the end of the airport runway. Just outside of the shipping lanes and 150 meters from the USS New York. Sunk by aircraft 19 November 1944 after running aground outside of Subic Bay on 17 November.
 
It is difficult to document the military life of the Seian Maru. Japanese records show that there were at least three ships in use (and sunk) with that name. In addition, records created in the war are often inaccurate. The Naval pilots that sank this ship identified her as merchant tanker. Japanese records show her as having been converted to a tanker and later converted back to a cargo vessel, which she is. We do know about her something. The ship is the Seian Maru, this is established beyond any doubt as the name is still faintly visible on the ships bow. She ran aground outside of Subic Bay on the 17th November. Refloated she made into Subic Bay escorted by a submarine chaser (CH36). On 19th November aircraft sank both vessels. CH36 is not a know dive site.

 Built in 1938 along with a sister ship Hokuan Maru, she was 351 feet long and 50 feet wide. Powered by diesel engines she could cruise at 12 knots with a top speed of 13 knots and a radius of 9,500 miles. In addition to her crew facilities, she was capable of carrying nine passengers