Two classes and a one-ship class of

submarine A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...

are known as the M class *

Soviet M-class submarine The M-class submarines, also ''Malyutka'' class (; ''baby'' or ''little one''), were a class of small, single-, or 1½-hulled coastal submarines built in the Soviet Union and used during World War II. The submarines were built in sections so th ...

, a class of 148

Soviet Navy The Soviet Navy was the naval warfare Military, uniform service branch of the Soviet Armed Forces. Often referred to as the Red Fleet, the Soviet Navy made up a large part of the Soviet Union's strategic planning in the event of a conflict with t ...

submarines built between 1933 and 1947 *

British M-class submarine The British Royal Navy M-class submarines were a small class of diesel-electric submarines built during World War I. The unique feature of the class design was a 12-inch (305 mm) gun mounted in a casemate forward of the conning tower. ...

, a class of 3

Royal Navy The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...

submarine monitors built in 1917 and 1918 * , a one-off United States submarine launched in 1915

See also