|Built By:||Armstrong Whitworth (Tyne)|
|Fate:||Sold for scrapping in February 1932.
Started life as K20.
In 1927 M2 and M3 had their large 12-inch guns removed in the late 1920s to conform with the Washington Disarmament Treaty, which stated that no submarine should have larger than 8-inch calibre guns.
M3 was converted to an experimental minelayer, stowing her 100 mines on rails inside a large free-flooding casing outside the hull. The mines were laid over her stern by means of a chain-conveyor belt. M3 was finally taken out of service in April 1932, and scrapped in 1933.
|04-12-1916 :||Laid Down|