U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. Although at times they were efficient fleet weapons against enemy naval warships, they were most effectively used in an economic-warfare role and enforcing a naval blockade against enemy shipping. The primary targets of the U-boat campaigns in both wars were the merchant convoys bringing supplies from Canada and other parts of the British Empire, and from the United States, to the United Kingdom and to the Soviet Union and the Allied territories in the Mediterranean. German submarines also targeted Brazilian merchant ships during both World Wars and, twice over, precipitated Brazil's decision to give up its neutral stance and declare war on Germany.
USS Dolphin (SF-10/SC-3/SS-169), a submarine and one of the "V-boats", was the sixth ship of the United States Navy to be named for that aquatic mammal. She also bore the name V-7 and the classifications SF-10 and SC-3 prior to her commissioning. She was launched on 6 March 1932 by the Portsmouth Navy Yard, sponsored by Mrs. E.D. Toland, and commissioned on 1 June 1932.
USS Argonaut (V-4/SF-7/SM-1/A-1/APS-1/SS-166) was a submarine of the United States Navy, the first boat to carry the name. Argonaut was laid down as V-4 on 1 May 1925 at Portsmouth Navy Yard. She was launched on 10 November 1927, sponsored by Mrs. Philip Mason Sears, the daughter of Rear Admiral William D. MacDougall, and commissioned on 2 April 1928. Although never officially designated as "SS-166", at some point she displayed this number on her conning tower.
USS Albacore (AGSS-569) is a unique research submarine that pioneered the American version of the teardrop hull form of modern submarines. The revolutionary design was derived from extensive hydrodynamic and wind tunnel testing, with an emphasis on underwater speed and maneuverability. She was the third vessel of the United States Navy to be named for the albacore.
The Balao class was a design of United States Navy submarine used during World War II, and with 120 boats completed, the largest class of submarines in the United States Navy. An improvement on the earlier Gato class, the boats had slight internal differences. The most significant improvement was the use of thicker, higher yield strength steel in the pressure hull skins and frames, which increased their test depth to 400 feet (120 m). Tang actually achieved a depth of 612 ft (187 m) during a test dive, and exceeded that test depth when taking on water in the forward torpedo room while evading a destroyer.
USS Bonita (SF-6/SS-165), a Barracuda-class submarine and one of the "V-boats," was the third ship of the United States Navy to be named for the bonito. Her keel was laid down by the Portsmouth Navy Yard. She was launched on 9 June 1925 as V-3 (SF-6), sponsored by Mrs. L.R. DeSteiguer, wife of Rear Admiral DeSteiguer, and commissioned on 22 May 1926, Lieutenant Commander Charles A. Lockwood, Jr. in command. Like her sisters, Bonita was designed to meet the fleet submarine requirement of 21 knots (39 km/h) surface speed for operating with contemporary battleships.
Tench-class submarines were a type of submarine built for the United States Navy (USN) between 1944 and 1951. They were an improvement over the Gato and Balao classes, only about 35 to 40 tons larger, but more strongly built and with a slightly improved internal layout. One of the ballast tanks was converted to carry fuel, increasing range from 11,000 nautical miles to 16,000 nautical miles. This improvement was also made on some boats of the previous two classes. Further improvements were made beginning with SS-435, which are sometimes referred to as the Corsair class. Initial plans called for 80 to be built, but 51 were cancelled in 1944 and 1945 when it became apparent that they would not be needed to defeat Japan. The remaining 29 were commissioned between October 1944 (Tench) and February 1951 (Grenadier). The last submarine of the Tench class, as well as the last submarine which served during World War II, remaining in service with the U.S. Navy was USS Tigrone (AGSS-419) which was decommissioned on 27 June 1975.
The Tang-class submarines were the first submarines designed and built by the United States Navy after WWII. They incorporated the best features of the high-speed German Type XXI U-boat and the venerable U.S. Navy fleet submarine. The Tang-class, with the fleet submarines converted under the Greater Underwater Propulsion Power (GUPPY) program, had much higher submerged performance than their predecessors, but were quickly surpassed by the nuclear-propelled submarines that entered service beginning in 1954. Six units in total were built.
USS Narwhal (SS-167), the lead ship of her class of submarine and one of the "V-boats", was the second ship of the United States Navy to be named for the narwhal. She was named V-5 (SC-1) when her keel was laid down on 10 May 1927 by the Portsmouth Navy Yard in Kittery, Maine.
USS Bass (SF-5/SS-164), a Barracuda-class submarine and one of the "V-boats", was the first ship of the United States Navy to be named for the bass.
USS Cachalot (SC-4/SS-170), a United States Navy submarine and the lead ship of her class, known as the "V-boats", was the only ship of the United States Navy to be named for the sperm whale. Her keel was laid down by the Portsmouth Navy Yard. She was launched on 19 October 1933 as V-8 (SC-4) sponsored by Miss K. D. Kempff, and commissioned on 1 December 1933 with Lieutenant Commander Merril Comstock in command. Cachalot was the first submarine to have the Torpedo Data Computer, Arma Corporation's Mark 1, installed.
The Tambor-class submarine was a United States Navy submarine design, used primarily during World War II. They were the USN's first fully successful fleet submarine, and began the war close to the fighting. Six of the class were in Hawaiian waters or the Central Pacific on 7 December 1941, with Tautog at Pearl Harbor during the attack. They went on to see hard service; seven of the twelve boats in the class were sunk before the survivors were withdrawn from front-line service in early 1945; this was the highest percentage lost of any US submarine class. Tautog was credited with sinking 26 ships, the largest number of ships sunk by a US submarine in World War II. The Tambors attained the top speed of 21 knots (39 km/h) and range of 11,000 nautical miles (20,000 km) of the preceding Sargo class, and improvements included six bow torpedo tubes, a more reliable full diesel-electric propulsion plant, and improved combat efficiency with key personnel and equipment relocated to the conning tower. In some references, the Tambors are called the "T Class", and SS-206 through SS-211 are sometimes called the "Gar class".
The Sargo-class submarines were among the first United States submarines to be sent into action after the Japanese attack on Pearl Harbor, starting war patrols the day after the attack, having been deployed to the Philippines in late 1941. Similar to the previous Salmon class, they were built between 1937 and 1939. With a top speed of 21 knots, a range of 11,000 nautical miles (20,000 km), and a reliable propulsion plant, along with the Salmons they were an important step in the development of a true fleet submarine. In some references, the Salmons and Sargos are called the "New S Class", 1st and 2nd Groups.
USS T-3 (SS-61/SF-3) was an AA-1-class submarine in the service of the United States Navy originally named AA-3.
The Barracuda-class submarines were the product of Project Kayo, a research and development effort begun immediately after World War II by the United States Navy to "solve the problem of using submarines to attack and destroy enemy submarines." They originally had the hull classification symbol SSK, for "hunter-killer submarine".
USS Mingo (SS-261) — a Gato-class submarine — was the first ship of the United States Navy to be named for the mingo snapper.
Air-independent propulsion (AIP), or air-independent power, is any marine propulsion technology that allows a non-nuclear submarine to operate without access to atmospheric oxygen. AIP can augment or replace the diesel-electric propulsion system of non-nuclear vessels.
The United States Navy Submarine Force Library and Museum is located on the Thames River in Groton, Connecticut. It is the only submarine museum managed exclusively by the Naval History & Heritage Command division of the Navy, and this makes it a repository for many special submarine items of national significance, including USS Nautilus (SSN-571). Visitors may take a 30-minute self-guided audio tour of the Nautilus.
The S-99 experimental submarine was the only ship of the Project 617 class that the Soviet Union built during the early Cold War. She was the only Soviet submarine which used a German Walter turbine fueled by high-test peroxide (HTP). Entering service in 1956, the boat was assigned to a training unit of the Baltic Fleet. S-99 was badly damaged by a HTP explosion in 1959 and was not repaired. The submarine was decommissioned in 1964 and subsequently scrapped.
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.
United States 
