A hell ship is a ship with extremely unpleasant living conditions or with a reputation for cruelty among the crew. It now generally refers to the ships used by the Imperial Japanese Navy and Army to transport Allied prisoners of war (POWs) and romushas (Asian forced labourers) out of the Dutch East Indies, the Philippines, Hong Kong and Singapore in World War II. The POWs were taken to Japan, Taiwan, Manchuria, Korea, the Moluccas, Sumatra, Burma or Siam to be used as forced labor. In Japanese they are called jigoku-sen (地獄船?), with the same literal meaning.
Early use of the term
The term was coined much earlier. During the American Revolution, HMS Jersey and other prison hulks in New York Harbor were used by the British to house American prisoners of war in terrible conditions. More than 11,000 prisoners died, more than all American battle deaths in the war. HMS Jersey in particular was referred to as "Hell."
The term was also used for German prisoner of war transports including the German tanker Altmark. The Royal Navy destroyer HMS Cossack boarded Altmark in a Norwegian fjord on 16 February 1940 and released some 300 British merchant sailors picked up from ships sunk by the pocket battleship Admiral Graf Spee. In reporting the Altmark Incident, British newspapers frequently called Altmark "Hitler's hell-ship" or the "Nazi hell-ship".
Japanese hell ships
In May 1942 the Japanese began transferring POWs by sea. Similar to treatment on the Bataan Death March, prisoners were often crammed into cargo holds with little air, food or water for journeys that would last weeks. Many died due to asphyxia, starvation or dysentery. Some POWs became delirious and unresponsive in their environment of heat, humidity and lack of oxygen, food, and water. These unmarked prisoner transports were targeted as enemy ships by Allied submarines and aircraft.
More than 20,000 Allied POWs died at sea when the transport ships carrying them were attacked by Allied submarines and aircraft. Although Allied headquarters often knew of the presence of POWs through radio interception and code breaking, the ships were sunk because interdiction of critical strategic materials was more important than the deaths of prisoners-of-war.
Lisbon Maru was carrying 2,000 British POWs from Hong Kong to Japan in appalling conditions when torpedoed by USS Grouper on 1 October 1942. 800 POWs died when the ship sank the following day. Many were shot or otherwise killed by the ship's Japanese guards.
Rakuyo Maru was torpedoed 12 September 1944 by USS Sealion which later realized the ship carried Allied POWs. Footage of some of the survivors subsequently being picked up by the submarine is available here
Suez Maru was a 4,645-ton freighter with passenger accommodation. She sailed on 25 November 1943 with 548 POW (415 British and 133 Dutch) from Ambon bound for Surabaya. The POWs were all sick men from the work-camps on the Moluccas and Ambon. Twenty were stretcher cases. On 29 November 1943 the ship was torpedoed by USS Bonefish near Kangean Island east of Madoera Island. Most of the POWs drowned in the holds of the ship. Those who escaped from the holds and left the ship were shot by the Japanese. There were no survivors.
Shinyo Maru was attacked by the submarine USS Paddle on 7 September 1944. Two torpedo hits sank the ship and killed several hundred US, Dutch and Filipino servicemen. Japanese guarding the prisoners opened fire on them while they were trying to abandon ship or swim to the nearby island of Mindanao. 47 Japanese and 687 Allied POWs were killed. 
The 5,065-ton tramp steamer Junyo Maru sailed from Batavia (Tandjoeng Priok) on 16 September 1944 with about 4,200 romusha slave labourers and 2,300 POWs aboard. These Dutch POWs included 1,600 from the 10th Battalion camp and 700 from the Kampong Makassar camp. This 23rd transport of POWs from Java was called Java Party 23. Java Party 23 included about 6,500 men bound for Padang on the west coast of Sumatra to work on the Sumatra railway (Mid-Sumatra).
On 18 September 1944 the ship was 15 miles off the west coast of Sumatra near Benkoelen when HMS Tradewind hit her with two torpedoes, one in the bow and one in the stern. About 4,000 romushas and 1,626 POWs died when the ship sank in 20 minutes. About 200 romushas and 674 POWs were rescued by Japanese ships and taken to the Prison in Padang, where eight prisoners died. 
The 600-ton Maros Maru (sometimes called Haruyoshi Maru) sailed from Ambon on 17 September 1944 routed along the south-coast of Celebes with about 500 British and Dutch POWs bound for Surabaya. On 21 September 1944 the ship arrived at Muna Island south of Celebes) to embark 150 POWs. The ship required engine repairs upon arrival in Makassar. Here 159 POWs died in the holds in the 40 days required to complete repairs. They got a seaman’s grave in the harbour of Makassar. Only 327 POWs survived when the ship reached Surabaya on 26 November 1944. They were transported by train to the Kampong Makassar camp in Batavia (Meester Cornelis), and arrived on 28 November 1944.
The Oryoku Maru was a 7,363-ton passenger cargo liner transporting 1,620 survivors of the Bataan Death March, Corregidor and other battles. It left Manila on 13 December 1944, and over the next two days was mistakenly bombed and strafed by US planes. About 270 died aboard ship. Some died from suffocation or dehydration. Others were killed in the attack or drowned while escaping the sinking ship. A colonel, in his official report, wrote:
- Many men lost their minds and crawled about in the absolute darkness armed with knives, attempting to kill people in order to drink their blood or armed with canteens filled with urine and swinging them in the dark. The hold was so crowded and everyone so interlocked with one another that the only movement possible was over the heads and bodies of others.
After Oryoku Maru sank in Subic Bay in December 1944, Enoura Maru was bombed in the harbor of Takao in January 1945.
Brazil Maru transported the last surviving Allied POWs to Moji, Japan. There the Japanese medics were shocked at the wasted condition of the POWs and used triage to divide them. The 110 most severe cases were taken to a primitive military hospital in Kokura where 73 died within a month. Four other groups were sent to Fukuoka POW camps 1, 3, 4 and 17. Of 549 men alive when the ship docked, only 372 survived the war. Some eventually went to a POW camp in Jinsen, Korea, where they were given light duty, mainly sewing garments for the Japanese Army.
- Jarvis, Adrian (January 2001). "A Gentleman's War? The Diary of Captain Albert Horace Brown of SS Huntsman". The Northern Mariner XI (1): 54.
- Simpson, Brian (2003). The Rule of Law in International Affairs. p. 215.
- Michno, Gregory F (2001). Death on the Hellships: Prisoners at Sea in the Pacific War. Annapolis, MD: Naval Institute Press.[page needed]
- 船舶輸送艦における遭難部隊資料（陸軍） - IJA report about military transport ship losses in WW2
- Mazza, Eugene A. "USS Paddle: Sinking American POWs". Memories of War: Personal Histories. The Pacific War: The US Navy. Retrieved 30 June 2013.
- Beekhuis, Henk (18 June 2013). "Junyo Maru". Japanse krijgsgevangenkampen. Henk Beekhuis. Retrieved 30 June 2013.
- "Junyo Maru". Roll of Honour. Retrieved 30 September 2008.
- Toland, John (1970). The Rising Sun: The Decline and Fall of the Japanese Empire 1936–1945. Random House. p. 601.
- POW Diary of Capt. P.R.Cornwall, National Archive Mil. Hist. Div. File 99-2-30 Book 6, and his letters
- U.S. National Archives, Mil. Hist. Div. POW diary of Capt. Paul R.Cornwall, 41-45, File 999-2-30 Bk.6 and unpublished letters.
- Jones, Allan (2002). The Suez Maru atrocity: Justice denied!: the story of Lewis Jones, a victim of a WW2 Japanese hell-ship. Hornchurch: privately published. ISBN 0954272501.
- "American POWs on Japanese Ships Take a Voyage into Hell". Prologue Magazine. Retrieved December 20, 2005.
- "Hell Ships". Britain at War. Retrieved January 16, 2008.
- Rolls of those who died on Hell Ships
-  documentary Hell Ships to Flores and the Moluccas. 2012. Kees Maaswinkel
-  documentary Hell ships to Sumatra. 2012. Kees Maaswinkel