In the early 1930s the Crichton-Vulcan shipyard in Turku built three 500-ton submarines of Vetehinen-class for the Finnish Navy. The German firm Ingenieurskantoor voor Scheepsbow den Haag that had been set up 1922 in the Netherlands to evade the peace treaty of Versailles, designed the vessels and supervised the building. The Vetehinen-class were a success and as the Germans did not have any experience of small coastal submarines they ordered a 250-ton submarine from Crichton-Vulcan in October 1930 and the Finnish government reserved the first-hand right to purchase the vessel. The ship, called CV-707 after its shipyard order number, was launched on May 10, 1933 and during the sailing-seasons 1933 and 1934 the German Navy carried out trials and maneuvers in the Turku achipelago. The CV-707 was accepted as a prototype after which six submarines of the Type IIA were built for the German Navy in the Deutsche Werke shipyard at Kiel.
The Finnish government took over the ship autumn 1934 and during the sailing season 1935 the submarine was in the Finnish Navy's service. When the Parliament appropriated the funds the ship was added to the fleet and named Vesikko.
During the sailing-seasons 1936 and 1938-1939 Vesikko was used for training and maneuvers together with other ships of the submarine flotilla. When the Winter War broke out on November 30, 1939 Vesikko was ordered on patrol and during December patrolled the Gulf of Finland. In December the vessel was docked for winter.
When war again broke out in June 1941 between Finland and the Soviet Union Vesikko and the other ships of the submarine flotilla were ordered out to the eastern Gulf of Finland. In July she torpedoed, east of Hogland, the Russian merchant Vyborg. During the sailing-seasons 1942 and 1943 Vesikko was in patrol and submarine reconnaissance service in the Gulf of Finland and the northern Baltic Sea, but due to vast mine fields and nets the Soviet fleet was isolated at Leningrad and Vesikko did not meet any targets to torpedo.
When the Soviet Union started the great offensive in the beginning of June 1944 on the Carelian Isthmus Vesikko was ordered to the eastern Gulf of Finland to cover the Finnish evacuation transports. According to the armistice of September 19, 1944 with the Soviet Union, the submarines were ordered back to their naval bases. In December 1944 Vesikko made her last voyage as a warship and in January 1945 the allied supervisory commission ordered the Finnish submarines to be disarmed.
The peace treaty of Paris in 1947 prohibited Finland to keep the submarines and they were all sold to Belgium as scrap iron in 1953, except Vesikko. In 1959 the ship was conveyed to the Military Museum to be put in order as a museum submarine. With the aid of donations from business firms and former submarine crew members Vesikko was transported in parts to Suomenlinna and reconstructed. On the Finnish Navy's anniversary July 9, 1973 Vesikko was opened to the public and as a last member of the submarine flotilla gives the visitor an unforgettable picture of the technical skill and the seamanship requirements, that the crew of a submarine had to master and of the surroundings in which they carried out their duty.