The Russian submarine AG-12 was an AG-class (AG = Amerikansky Golland) submarine which served in the Gulf of Finland during World War I. During the war, Russian submarines operated from bases in Finland. AG-12 and three of her sisters were scuttled in Hanko harbor on 3 April 1918, just prior to the German landing there. AG-12 and AG-16 seemed to be in relatively good shape and the Finns decided to salvage them. The submarine was transferred to Turku for repairs, although it proved to be hopeless, and she was soon scrapped.