Patrol 1

3 Aug 1943-27 Sep 1943

No Sinkings

Patrol 2

20 Oct 1943-12 Dec 1943

八幡丸 Yawata Maru

千早丸 Chihaya Maru

大洲丸 Daishu Maru

さんらもん丸 San Ramon Maru

Note: : うめ丸 Ume Maru, credited to Seahorse in JANAC, but was most likely sunk by USS Trigger (SS-237)

Patrol 3

6 Jan 1944-16 Feb 1944

日光丸 Nikko Maru

やすくに丸 Yasukuni Maru

生駒丸 Ikoma Maru

東晃丸 Toko Maru

藤影丸 Toei Maru

Patrol 4

16 Mar 1944-11 May 1944

新玉丸 Aratama Maru

木津川丸 Kizugawa Maru

美作丸 Mimasaka Maru (listed as Bisaku Maru in JANAC)

秋川丸 Akigawa (or Akikawa) Maru

Note: 呂45 RO 45, credited to Seahorse in JANAC, was not sunk at this time.

Patrol 5

11 Jun 1944-19 Jul 1944

うすり丸 Ussuri (or Usuri) Maru - shared credit with aircraft; JANAC credits aircraft only.

めだん丸 Medan Maru

日東丸 Nitto Maru

暁勇丸 Gyoyu Maru

第二十八共同丸 Kyodo Maru No. 28

Patrol 6

1944-18 Oct 1944

Patrol 7

9 Mar 1945-1945

Patrol 8

12 Jul 1945-1945

ships, tons ( were small vessel often not included in sinkings)

JANAC - ships, tons. Note that the criteria JANAC used included all Japanese Naval vessels (although JANAC did not usually count warships less than 500 tons that were converted from merchant ships) and all Japanese merchant vessels of 500 or more gross tons known or believed to have been lost during the war. Differences between JANAC figures and current research are noted above.

Alden-McDonald credit Seahorse with ships and tons sunk.

SORG credits Seahorse with ships and tons sunk.

Japanese Naval and Merchant Ship Losses - JANAC on the NHHC website

JANAC on the Hyperwar website - https://www.ibiblio.org/hyperwar/Japan/IJN/JANAC-Losses/JANAC-Losses-6.html

SORG- http://archive.hnsa.org/doc/subreports-sorg.htm (Excel spreadsheet download)

Archives of the Pacific Fleet Submarine Museum (PFSM)

War Patrol Reports - USS Seahorse

Monthly Losses of Combatant and Non-Combatant Vessels

太平洋戦争時の喪失船舶明細表（汽船主体）- Lost Vessel table during the Pacific War (merchant vessels)

Alden, John D., and McDonald, Craig R. - U.S. & Allied Sub Successes in the Pacific & Far East during WWII - Fourth Edition, 2009

Cressman, Robert - The Official Chronology of the U.S. Navy in World War II, Naval Institute Press, 2000.

Wrecksite - https://www.wrecksite.eu/wrecksite.aspx

Miramar Ship Index - https://www.miramarshipindex.nz/

Imperial Japanese Navy Page - http://www.combinedfleet.com/

Wikipedia Japan - https://ja.wikipedia.org/wiki/

Japan Center for Asian Historical Records - National Archives of Japan - https://www.jacar.go.jp/index.html

Official U.S. Navy Photos - Naval History & Heritage Command

Archives of the Pacific Fleet Submarine Museum (PFSM)

Imperial Japanese Navy Page - http://www.combinedfleet.com/

Japanese Merchant Ship photos - Wrecksite - copyright owners retain all rights. Photos used on this site will be taken down should the owner request their removal.