HMS Astute (P447) was an Amphion-class submarine. Her keel was laid down by Vickers at Barrow-in-Furness. She was launched in 1944 and commissioned in 1945.
A midget submarine is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to six or nine, with little or no on-board living accommodation. They normally work with mother ships, from which they are launched and recovered and which provide living accommodation for the crew and support staff.
HMS Sceptre (P215) was a third-batch S-class submarine built for the Royal Navy during World War II. Completed in April 1943, she spent the majority of her career in the North Sea, off Norway. After an uneventful patrol, the submarine participated in Operation Source, an attack on German battleships in Norway using small midget submarines to penetrate their anchorages and place explosive charges. However, the midget submarine that she was assigned to tow experienced technical difficulties and the mission was aborted. During her next four patrols, Sceptre attacked several ships, but only succeeded in severely damaging one. She was then ordered to tow the submarine X24, which was to attack a floating dry dock in Bergen. The operation, codenamed Guidance, encountered difficulties with the attacking submarine's charts, and the explosives were laid on a merchant ship close to the dock instead. The dock was damaged and the ship sunk, and X24 was towed back to England. Sceptre then conducted a patrol in the Bay of Biscay, sinking two German merchant ships, before being reassigned to tow X24 to Bergen again. The operation was a success, and the dry dock was sunk.
Human torpedoes or manned torpedoes are a type of diver propulsion vehicle on which the diver rides, generally in a seated position behind a fairing. They were used as secret naval weapons in World War II. The basic concept is still in use.
Ghadir is a class of midget submarines built by Iran specifically for cruising within the shallow waters of the Persian Gulf. The Islamic Republic of Iran Navy is the sole operator of this class, whose all submarines serve in the Southern Fleet. No submarine of this class is active at the Northern Fleet, i.e. the Caspian Sea.
The Nahang is an Iranian-made class of midget submarine designed for shallow water operations. Only one prototype of this class is known to be completed, although its characteristics have remained unclear.
HMS H10 was a British H-class submarine built by the Canadian Vickers Co., Montreal. She was laid down on an unknown date and was commissioned in June 1915.
HMS Syrtis was a third-batch S-class submarine built for the Royal Navy during the Second World War. Completed in 1943, Syrtis spent most of her career in the Arctic, off Norway, other than a single patrol in the Bay of Biscay,
HMS Sea Nymph was a S-class submarine of the third batch built for the Royal Navy during World War II. Completed in July 1942, she spent the majority of her career patrolling the waters off Norway in the North Sea, then was sent to the Pacific but was forced back due to technical problems.
HMS Spark was a S-class submarine of the third batch built for the Royal Navy during World War II. She survived the war and was scrapped in 1950.
The Shershen class was the NATO reporting name for a class of torpedo boats built for the Soviet Navy and allies. The Soviet designation was Project 206 Shtorm.
The CB class was a group of midget submarines built for the Italian Navy during World War II. However, they were also used by several other navies, seeing action in the Mediterranean and in the Black Sea.
The Korean People's Army Navy or the Korean People's Navy (KPN), is the naval component of the Korean People's Army, the North Korean armed forces.
The Una-class submarine was a class of six midget submarines built for the Yugoslav Navy at the Brodogradilište specijalnih objekata during the 1980s. They were designed with the purpose of laying small minefields and transporting naval special forces, with or without their submersibles, in shallow waters that were inaccessible for larger submarines. Due to their mission profile that called for a small design as well as the need to stay undetected, they lacked torpedo armament and a generator for battery recharging.
I-16 was one of five Type C cruiser submarines of the C1 sub-class built for the Imperial Japanese Navy, Commissioned in 1940, she deployed a midget submarine for the attack on Pearl Harbor and for an attack on ships at Diego-Suarez in Madagascar, conducted an anti-shipping patrol in the Indian Ocean, and took part in the Guadalcanal campaign, New Guinea campaign, and Bougainville campaign before she was sunk in May 1944.
I-18 was one of five Type C cruiser submarines of the C1 sub-class built for the Imperial Japanese Navy. During World War II, she operated as the mother ship for a midget submarine during the attack on Pearl Harbor and the attack of Diego-Suarez, conducted a war patrol in the Indian Ocean, and served in the Guadalcanal campaign before she was sunk in February 1943.
I-48 was the last of three Type C cruiser submarines of the C2 sub-class built for the Imperial Japanese Navy. Commissioned in September 1944, she operated as a kaiten manned suicide attack torpedo carrier during World War II and was sunk in January 1945.
Ha-108 was an Imperial Japanese Navy Ha-101-class submarine. Designed as a transport submarine, she was completed and commissioned in May 1945 as a submarine tender for midget submarines. She served during the final months of World War II, surrendered at the end of the war in September 1945, and was scuttled in April 1946.
Ha-109 was an Imperial Japanese Navy Ha-101-class submarine. Completed as a transport submarine, she was converted into a submarine tender for midget submarines. She served during the final months of World War II, surrendered at the end of the war in September 1945, and was scuttled in April 1946.
Ha-111 was an Imperial Japanese Navy Ha-101-class submarine. Converted during construction into a submarine tender for midget submarines, she was completed and commissioned in July 1945, only a few weeks before the end of World War II, the last Ha-101-class submarine to be completed. She surrendered at the end of the war in September 1945, and was scuttled in April 1946.
North Korea [8] 
Vietnam: Purchased in 1997. [2] These were used by Vietnam People's Navy for swimmer delivery operations aside from conventional submarine operations. [2] The purchase was done by bartering. [9] Kim Jong-il personally approved of the delivery to make amends for not paying Vietnam for purchasing 20,000 tons of rice. [10] 
Cuba: Classified as a 'Delfin-class submarine' and is rumored to have either been built in North Korea or locally assembled in Cuba with North Korean assistance. [11] [12] 
