Ship History
Built in 1936 as a commercial oil tanker for Nippon Tanker Kabushiki Kaisha, Tokyo, with radio call sign JJGK. This tanker was capable of carrying 95,000 bbls (42 gal). The ship was powered by a diesel, single screw engine 1,163 NHP.

On March 21, 1941 the tanker visited San Francisco. Later in 1941, Hoyo was assigned to the Japanese Navy and attached to the Kure Naval District, for use as an oilier for the 4th Fleet. In Navy use, a triad kingpost added to the deck.

Wartime History
Hoyo Maru participated in Operation MO during April-May 1942, the planned invasion of Port Moresby, that resulted in the Battle of the Coral Sea, and saw the invasion force turn back.

Attacked by a US submarine on December 19, 1942 at Lat 18 degrees, 55' N and 150 degrees 16' E. This claim can not be linked to a know American submarine activity. Afterwards, Hoyo Maru was based at Truk and supplied fuel to bases in the central Pacific.

On November 5, 1943 the tanker departed Truk for Palembang and Singapore. The ship was spotted the next day by USS Haddock and attacked from the surface with its deck gun and torpedoes at 7 degrees 54' N, 150 degrees 6' E. Fires were caused and flooding in the aft compartments, and the ship began to drift. 90 of the crew were rescued (13 wounded). By 1710, the fires were under control and was taken under tow back to Truk, arriving November 10.

On February 4, 1944, the Hoyo Maru was moored in an area for ships awaiting repairs by repair ship Akashi between Dublon and Fefan Island, and photographed by Allied photo reconnaissance. It was misidentified as being east of Dublon in another photo taken that same day.

Sinking History
On February 17, 1944 the ship was strafed during the USN "Operation Hailstone" attack and dive bombed (Strike 1EE) by SBD Dauntless from the USS Enterprise and TBF Avengers from USS Yorktown. Bomb hits sank the already damaged ship, causing it to capsize and sink. Six crew aboard were killed during the attack.

The ship was photographed with the keel and stern above water. The ship remained in this position until the end of April, when it was again photographed. Since then, the wreck settled into deeper water.

Shipwreck
Sunk 400 yards off Fefan Island. This wreck is visible from the air, and the bow is only 8-12' deep and is encrusted with coral. The ship's name is visible on the starboard bow area (the 'H' is missing), identified by Dan Baliey, but dived since the earliest days at Truk.

The ship was heavily damaged when sinking, fires and capsizing. A large split is visible amidships, nearly 15' wide from bomb damage, the wreck can be entered through this break into the damaged engine room, also a lot of sediment. Collapsed deck structure prevents further exploration.

Ahead of the bridge is a paravane attached to the port side, and heavy silt in the forecastle, with rolls of cable and paint cans. The bow also has a 30' hole and a gun platform, the weapon is missing (possibly removed during repair and emplaced ashore). The damage the ship received before finally sinking was extensive. The wreck is dangerous to enter and there is lots of silt inside.

On June 28, 2006 the shipwreck was observed leaking oil and photographed by Michael Barrett. His photograph appears at "Pacific Shipwrecks Potentially Toxic Time Bombs".

Reference
Lagoon of Lost Ships includes dive footage of this wreck in 1969
WWII Wrecks of the Truk Lagoon pages 101-102, 116, 142, 147, 152, 165, 266-267, 352-356
Ghost Fleet of the Truk Lagoon, page 120
National Geographic "Pacific Shipwrecks Potentially Toxic Time Bombs" November 28, 2008 photo by Michael Barrett

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Last Updated
August 4, 2020