''Vesihiisi'' was a Finnish 500-tonne that was constructed in the early 1930s. The vessel served in the

Finnish Navy The Finnish Navy ( fi, Merivoimat, sv, Marinen) is one of the branches of the Finnish Defence Forces. The navy employs 2,300 people and about 4,300 conscripts are trained each year. Finnish Navy vessels are given the ship prefix "FNS", short for ...

during the

second World War World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

German design ''Iku-Turso'', ''Vesihiisi'', ''Vetehinen''

While preparing the design of the , the Germans also prepared a design for a seagoing submarine for the Finnish Navy. Three submarines were built to this design, and like ''Saukko'', they were fitted for mine-laying, the mines being supplied by the Germans. Being designed for use against Soviet bases (never very far from the Finnish bases), radius of action was not of prime importance to this design, and only 20 tons of fuel oil were carried (as opposed to the 67 tons carried by the German Type VIIa based on this design.

Combat operations

Winter War

''Vesihiisi'' was alerted with ''Vesikko'' to

Hanko Hanko may refer to People *August Hanko (military personnel), August Hanko, German First World War flying ace Places *Hanko, Finland, town and municipality *Hanko Peninsula, Finland *Hankø, an island in the Oslo Fjord in Norway *The asteroid ...

region on 30 November 1939 as several Soviet surface combatants were headed towards the area. The submarines however failed to arrive to the area in time to intercept the and its escorts. ''Vesihiisi'' ran aground in early December 1941 and had to be docked for a few days for repairs. On 27 December ''Vesihiisi'' laid 16 mines off the Soviet naval station of

Paldiski Paldiski is a town and Baltic Sea port situated on the Pakri Peninsula of northwestern Estonia. Since 2017, it's the administrative centre of Lääne-Harju Parish of Harju County. Previously a village of Estonia-Swedes known by the historical ...

but soon after the ice forced the submarine to stay in port.

Continuation War

''Vesihiisi'' started the Continuation War on 22 June by laying 20 mines in

Estonia Estonia, formally the Republic of Estonia, is a country by the Baltic Sea in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the sea across from Sweden, to the south by Latvia, a ...

n waters (controlled at the time by the

Soviet Union The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, it was nominally a federal union of fifteen national ...

). She laid 18 more mines on 24 June at Ruuskeri south southwest from

Gogland Gogland or Hogland (russian: Гогланд, transliteration from original sv, Hogland; fi, Suursaari) is an island in the Gulf of Finland in the eastern Baltic Sea, about 180 km west from Saint Petersburg and 35 km from the coas ...

and further 18 mines on 26 June southeast from

Bolshoy Tyuters Bolshoi Tyuters (russian: Большой Тютерс; fi, Tytärsaari; et, Suur Tütarsaar; sv, Tyterskär) is an island in the Gulf of Finland of the Baltic Sea, located away from the coast of Finland, to the south-east from Hogland. The is ...

. After this the mining operation was postponed and ''Vesihiisi'' laid the 18 already loaded mines finally on 2 August east of

Osmussaar Osmussaar ( sv, Odensholm, german: Odinsholm) is an Estonian island situated in the mouth of the Gulf of Finland in the Baltic Sea, 7.5 km off the Estonian mainland. Administratively the island is part of Lääne-Nigula Parish in Lääne ...

. On 2 July 1941 ''Vesihiisi'' while patrolling east of

encountered an escorted freighter heading east. A torpedo attack failed and the submarine suffered light damage from the escort's depth charges. On 5 August 1941 ''Vesihiisi'' attacked a convoy transporting supplies to besieged Soviet garrison at Hanko. According to Finnish sources, the convoy consisted of a transport vessel of ''Molotov'' class () escorted by pair of large

minesweepers A minesweeper is a small warship designed to remove or detonate naval mines. Using various mechanisms intended to counter the threat posed by naval mines, minesweepers keep waterways clear for safe shipping. History The earliest known usage of ...

and group of

patrol boats A patrol boat (also referred to as a patrol craft, patrol ship, or patrol vessel) is a relatively small naval vessel generally designed for coastal defence, border security, or law enforcement. There are many designs for patrol boats, and the ...

. According to Soviet sources, there were only four minor ships: the 489-ton freighter ''Hilde'', built in 1894, one

T58-class minesweeper The T58 class were a group of minesweepers built for the Soviet Navy in the 1950s. The Soviet designation was Project 264. Design The specification for these ships was issued in 1949 and the lead ship was completed in 1957. These ships were lar ...

, and two MO-class patrol boats. The submarine penetrated the escort screen and launched two torpedoes at a range of while being between the target and the escorts. Neither of the torpedoes exploded and the escorts forced ''Vesihiisi'' to dive to the depth of . Though the submarine did not suffer severe damage from the depth charges the repairs on the dock lasted for a week. In December 1941 after the Soviets had evacuated Hanko the Finnish submarines were docked for the winter. During the sailing season of 1941 the Italian torpedoes ''Vesihiisi'' used (Finnish designation T/40) proved to be unreliable. During 1942 ''Vesihiisi'' was upgraded with new 12-hydrophone listening arrays and equipped with depth charge rack capable of carrying 4 depth charges. The submarine was further modified by streamlining the tower and moving the 20 mm gun up to the tower. On 9 August 1942, ''Vesihiisi'' was deployed along with her two sister ships to

Mariehamn Mariehamn ( , ; fi, Maarianhamina ; la, Portus Mariae) is the capital city, capital of Åland, an autonomous territory under Finland, Finnish sovereignty. Mariehamn is the seat of the Government of Åland, Government and Parliament of Åland, ...

. Their mission was to conduct anti-submarine and escort operations in the

Sea of Åland The Åland Sea (or the Sea of Åland; sv, Ålands hav, fi, Ahvenanmeri) is a waterway in the southern Gulf of Bothnia, between Åland and Sweden. It connects the Bothnian Sea with the Baltic Sea proper. The western part of the basin is in Swed ...

. In the evening of 21 October 1942 she torpedoed and sank the

Soviet The Soviet Union,. officially the Union of Soviet Socialist Republics. (USSR),. was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 to 1991. A flagship communist state, ...

S-class submarine , near

Lågskär Lågskär (Swedish for "low skerry") is a small island within the Åland's archipelago of Finland. It belongs to the municipality of Lemland. It is situated about south of Mariehamn in the Baltic's Sea of Åland. The main island of Lågskär ...

in the

. The captain (Sergei Lisin) and three of the crew of ''S-7''; all of whom had been in the submarine's tower, were then captured (a fourth crewman drowned before he could be rescued). On 4 July 1944 ''Vesihiisi'' laid 20 mines between

Moshchny Island Moshchny (russian: Мощный; fi, Lavansaari; sv, Lövskär, et, Lavassaar) is an island in the Gulf of Finland of the Baltic Sea, located some 120 km west of Saint Petersburg. The island is a part of the Leningrad Oblast, Russia. The a ...

(Lavansaari) and

Seskar Seskar ( fi, Seiskari) ( sv, Seitskär) (russian: Сескар) is an island in the Gulf of Finland, part of the Leningrad Oblast of Russia. The island was an independent municipality of Finland populated by Finns at least since 16th century, un ...

(Seiskari). The boat was attacked with depth charges by two Soviet minesweepers but was able to escape without any damage. The submarine laid further 18 mines north of

on 6 July 1944.

Notes and references

{{DEFAULTSORT:Vesihiisi Vetehinen-class submarines Ships built in Turku 1930 ships World War II submarines of Finland