Submarine Seahorse (SS-304) (2024)

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Seahorse

Country	United States
Ship Class	Balao-class Submarine
Hull Number	SS-304
Builder	Mare Island Navy Yard
Laid Down	1 Jul 1942
Launched	9 Jan 1943
Commissioned	31 Mar 1943
Decommissioned	2 Mar 1946
Displacement	1,550 tons standard; 2,424 tons submerged
Length	312 feet
Beam	27 feet
Draft	17 feet
Machinery	Four Fairbanks-Morse Model 38D8-1/8 9-cyl diesel engines (5,400shp), four Elliott electric motors (2,740shp), two 126-cell Sargo batteries, two propellers
Speed	20 knots
Range	11,000nm at 10 knots surfaced, 48 hours at 2 knots submerged
Crew	81
Armament	6x533mm forward torpedo tubes, 4x533mm aft torpedo tubes, 24 torpedoes, 1x127mm deck gun
Submerged Speed	8.75 knots

Contributor: C. Peter Chen

ww2dbaseUSS Seahorse was commissioned into service in Mar 1943. After shakedown and training cruises, she departed the west coast of the United States for Pearl Harbor, US Territory of Hawaii, from where she would embark on her first war patrol in Aug 1943. She would make a total of eight war patrols, most of which saw her sinking Japanese vessels ranking from small sail boats to large cargo ships; on 20 Apr 1944, she encountered a warship, Japanese submarine RO-45, and promptly destroyed her as well. She ended the war while on lifeguard station 40 miles southeast of Hachijo Jima of Izu Islands south of Japan, about 250 kilometers south of Tokyo, Japan. She was decommissioned from service at Mare Island Naval Shipyard at Vallejo, California, United States in Mar 1946 and was placed in reserve until she was removed from the US Navy Register in Mar 1967. She was sold for scrap in the following year.

ww2dbaseSource: Wikipedia

Last Major Revision: Apr 2013

Submarine Seahorse (SS-304) Interactive Map

USS Seahorse arrived at Brisbane, Australia, ending her fourth war patrol.

11 Jun 1944

USS Seahorse departed Brisbane, Australia for her fifth war patrol.

", -27.472778000, 153.027778, 2], ["

Pacific Ocean

16 Jan 1944

USS Seahorse sank Japanese cargo ship Nikko Maru off the Mariana Islands, hitting her with three of four torpedoes fired.

", 12.490000000, 150.19, 1], ["

Pearl Harbor, Oahu, Hawaii

03 Aug 1943

USS Seahorse departed Pearl Harbor, US Territory of Hawaii for her first war patrol.

12 Dec 1943

USS Seahorse arrived at Pearl Harbor, US Territory of Hawaii, ending her second war patrol.

06 Jan 1944

USS Seahorse departed Pearl Harbor, US Territory of Hawaii for her third war patrol.

16 Feb 1944

USS Seahorse arrived at Pearl Harbor, US Territory of Hawaii, ending her third war patrol.

16 Mar 1944

Honolulu, Oahu, Hawaii

19 Jul 1944

USS Seahorse sank arrived at Pearl Harbor, US Territory of Hawaii, ending her fifth war patrol.

", 21.349270000, 202.05603, 1], ["

Midway, US Pacific Islands

27 Sep 1943

USS Seahorse arrived at Midway Atoll, ending her first war patrol.

20 Oct 1943

USS Seahorse departed Midway Atoll for her second war patrol.

18 Oct 1944

USS Seahorse arrived at Midway Atoll, ending her sixth war patrol.

", 28.201389000, 182.618611, 3], ["

Midway, US Pacific Islands

29 Sep 1943

", 28.218573000, 182.632231, 1], ["

Vallejo, California, United States

03 Jan 1946

1946

28 Sep 1950

", 38.090000000, -122.263333, 3], ["

Vallejo, California, United States

01 Jul 1942

The keel of submarine Seahorse was laid down at Mare Island Naval Shipyard, Vallejo, California, United States.

09 Jan 1943

Submarine Seahorse was launched at Mare Island Naval Shipyard, Vallejo, California, United States, sponsored by the wife of Chester C. Smith.

02 Mar 1946

USS Seahorse was decommissioned from service at Mare Island Naval Shipyard at Vallejo, California, United States.

", 38.097588000, -122.267734, 3], ["

Vallejo, California, United States

Jan 1946

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Photographs

See all 7 photographs of Submarine Seahorse (SS-304)

Seahorse Operational Timeline

1 Jul 1942	The keel of submarine Seahorse was laid down at Mare Island Naval Shipyard, Vallejo, California, United States.
9 Jan 1943	Submarine Seahorse was launched at Mare Island Naval Shipyard, Vallejo, California, United States, sponsored by the wife of Chester C. Smith.
31 Mar 1943	USS Seahorse was commissioned into service with Commander Donald McGregor in command.
3 Aug 1943	USS Seahorse departed Pearl Harbor, US Territory of Hawaii for her first war patrol.
29 Aug 1943	USS Seahorse attempted to attack a Japanese convoy in the Pacific Ocean, but was counterattacked prior to the launching of torpedoes. She suffered minor damage from depth charges.
6 Sep 1943	USS Seahorse sank a Japanese transport in the Palau Islands, hitting her with three of four torpedoes fired. The subsequent depth charge counterattack caused severe leaks.
14 Sep 1943	USS Seahorse attacked a Japanese tanker in the Palau Islands; all eight torpedoes missed.
27 Sep 1943	USS Seahorse arrived at Midway Atoll, ending her first war patrol.
20 Oct 1943	USS Seahorse departed Midway Atoll for her second war patrol.
29 Oct 1943	USS Seahorse sank a small Japanese vessel with her deck gun south of Japan.
30 Oct 1943	USS Seahorse sank a small Japanese vessel with her deck gun south of Japan.
31 Oct 1943	USS Seahorse sank a small Japanese vessel with her deck gun south of Japan.
2 Nov 1943	USS Seahorse sank Japanese cargo ships Chihaya Maru and Ume Maru south of Japan; nine torpedoes were expended during this attack, seven of which hit.
22 Nov 1943	USS Seahorse sank Japanese cargo ship Daishu Maru south of Japan, hitting her with two of four torpedoes fired.
26 Nov 1943	USS Seahorse sank Japanese tanker San Ramon Maru south of Japan, hitting her with two of three torpedoes fired.
1 Dec 1943	USS Seahorse damaged a Japanese transport south of Japan, hitting her with two of four torpedoes fired. She ran out of torpedoes and set sail for Hawaii Islands.
12 Dec 1943	USS Seahorse arrived at Pearl Harbor, US Territory of Hawaii, ending her second war patrol.
6 Jan 1944	USS Seahorse departed Pearl Harbor, US Territory of Hawaii for her third war patrol.
16 Jan 1944	USS Seahorse sank Japanese cargo ship Nikko Maru off the Mariana Islands, hitting her with three of four torpedoes fired.
21 Jan 1944	USS Seahorse sank Japanese cargo ship Yasukuni Maru and passenger-cargo ship Ikoma Maru in the Pacific Ocean, expending nine torpedoes, five of which scored hits.
28 Jan 1944	USS Seahorse began an 80-hour chase of a Japanese convoy off the Palau Islands.
30 Jan 1944	USS Seahorse sank Japanese cargo ship Toko Maru south of Japan, which she had been chasing for many hours, hitting her with all three of three torpedoes fired.
31 Jan 1944	USS Seahorse sank Japanese cargo ship Toei Maru south of Japan, which she had been chasing for many hours, hitting her with two of eight torpedoes fired.
16 Feb 1944	USS Seahorse arrived at Pearl Harbor, US Territory of Hawaii, ending her third war patrol.
16 Mar 1944	USS Seahorse departed Pearl Harbor, US Territory of Hawaii for her fourth war patrol.
8 Apr 1944	USS Seahorse detected a Japanese convoy off the Mariana Islands. After dark, attacked the convoy and sank cargo ship Kizugawa Maru, hitting her with four of eight torpedoes fired. After evading depth charges, she attacked again, sinking cargo ship Bisaku Maru, hitting her with two of six torpedoes fired.
12 Apr 1944	USS Seahorse assumed lifeguard station duty for US aircraft attacking Saipan, Mariana Islands.
20 Apr 1944	USS Seahorse sank Japanese submarine RO-45 west of Saipan, Mariana Islands, hitting her with three of four torpedoes fired.
27 Apr 1944	USS Seahorse sank Japanese cargo ship Akigawa Maru west of Saipan, Mariana Islands.
3 May 1944	USS Seahorse was relieved from lifeguard station duty in the Mariana Islands and set sail for Milne Bay, Australian Papua.
11 May 1944	USS Seahorse arrived at Brisbane, Australia, ending her fourth war patrol.
11 Jun 1944	USS Seahorse departed Brisbane, Australia for her fifth war patrol.
27 Jun 1944	USS Seahorse sank Japanese tanker Medan Maru and damage two other ships off Taiwan, hitting them with five of six torpedoes fired.
3 Jul 1944	USS Seahorse sank Japanese cargo ship Nitta Maru and passenger-cargo ship Gyoyu Maru off Taiwan, hitting her with four of five torpedoes fired.
4 Jul 1944	USS Seahorse sank Japanese cargo ship Kyodo Maru No. 28 off Taiwan, hitting her with five of her last six torpedoes.
19 Jul 1944	USS Seahorse sank arrived at Pearl Harbor, US Territory of Hawaii, ending her fifth war patrol.
6 Oct 1944	USS Seahorse claimed the sinking of a Japanese destroyer off Taiwan with one torpedo hit of six torpedoes fired.
18 Oct 1944	USS Seahorse arrived at Midway Atoll, ending her sixth war patrol.
9 Mar 1945	USS Seahorse departed for her seventh war patrol.
8 Apr 1945	USS Seahorse sank a small Japanese vessel with gunfire off Japan.
18 Apr 1945	USS Seahorse was damaged by two Japanese patrol vessels off Japan; she fired one torpedo in return, but it missed. She set sail for Guam, Mariana Islands for repairs.
12 Jul 1945	USS Seahorse departed Pearl Harbor, US Territory of Hawaii for her eighth war patrol.
2 Mar 1946	USS Seahorse was decommissioned from service at Mare Island Naval Shipyard at Vallejo, California, United States.
6 Nov 1962	USS Seahorse was reclassified an auxiliary submarine and was given the new hull number AGSS-304.
1 Mar 1967	Submarine Seahorse was struck from the US Naval Register.
4 Dec 1968	Submarine Seahorse was sold to Zidell Explorations, Inc. of Portland, Oregon, United States for scrapping.

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Visitor Submitted Comments

1. Jeff says:
12 Feb 2013 03:43:03 PM

I found a large orange buoy at a salvage yard that had a plaque on it that said, The other end of the cable attatched to this buoy is secured to a sunken submarine, USS Sea Horse (space between Sea and Horse is there) Do not pull on this cable with a force greater than 5,000 pounds. There is the same information in another language under that. Anyone have any information on which boat that could have been hooked to? I was told it was possibly from Italy. Thank you.

2. Anonymous says:
8 Dec 2015 07:19:52 AM

You found a Rescue Buoy from the USS Seahorse, SSN-669. Submarine was decommissioned and scrapped in the 1990's. You might find a few of her old crew interested in that plaque. Piece of Serious Memorabilia for us.

3. V. Penprase says:
24 Jul 2017 06:08:50 AM

My father was an electrician on the Seahorse, he told us stories about wartime, but never told " secret orders" he was sworn to. I wish he could have seen this site! He passed away in 2008. All oh his kids and grandkids have a seahorse tatted somewhere on our bodies in honor of dad. He was a proud and honorable American until the day he died. Thank you for this site!

4. Anonymous says:
15 May 2018 07:15:34 PM

Isn't it about time to reveal the circ*mstances accurately. Please GOD, it is time for the truth. The records need to be released if they are not already. The truth will set us free, lies and deception will continue to entangle us in the web of destruction.

5. Leo Berger-Greer says:
4 Oct 2018 10:37:10 AM

My Great Uncle, Harry Holt Greer,
was the captain. We have his box of lead Japanese warship models and the original film reel of the movie about him, which you can find on youtube.

6. Anonymous says:
15 Nov 2018 05:40:04 PM

Does anyone remember Charles Paul Wilcox he was a chief on the Seahorse

7. Anonymous says:
10 Jul 2019 07:11:42 PM

Hi I'm trying to help a friend out his name is Alan van he was the Torpedoes mate on the USS seahorse and World War II just trying to find the crew roster for him

All visitor submitted comments are opinions of those making the submissions and do not reflect views of WW2DB.

Search WW2DB

Submarine Seahorse (SS-304) (2024)

Seahorse

Pacific Ocean

Pearl Harbor, Oahu, Hawaii

Honolulu, Oahu, Hawaii

Midway, US Pacific Islands

Midway, US Pacific Islands

Vallejo, California, United States

Vallejo, California, United States

Vallejo, California, United States

References