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

Finnish Navy The Finnish Navy ( , ) 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 "Finnish Navy ship", but ...

during the

second World War World War II or the Second World War (1 September 1939 – 2 September 1945) was a World war, global conflict between two coalitions: the Allies of World War II, Allies and the Axis powers. World War II by country, Nearly all of the wo ...

. The name ''Vesihiisi'' refers to a mythological Finnish sea creature similar to a Siren.

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), the 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 the Hanko region on 30 November 1939 as several Soviet surface combatants were headed towards the area. The submarines however failed to reach 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 seaside Populated places in Estonia, town in northwestern Estonia, located on the Pakri Peninsula and adjacent Pakri Islands, Pakri islands in the Gulf of Finland of the Baltic Sea. It is the administrative centre of the Lääne- ...

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

Continuation War

''Vesihiisi'' commenced operations during the Continuation War on 22 June by laying 20 mines in

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

n waters (controlled at the time by the

Soviet Union The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

). She laid 18 more mines on 24 June at Ruuskeri south-southwest of Suursaari Island (

Gogland Gogland or Hogland (, transliteration from original ; , German: ''Hochland'') 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 coast of Finland (near Kotka) ...

) and further 18 mines on 26 June southeast of Tytärsaari (

Bolshoy Tyuters Bolshoi Tyuters (; ; ; ) 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 island is a part of the Leningrad Oblast, Russia. The area is approximately . There are ...

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

Osmussaar Osmussaar (, ) 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 County. Its area is . Before th ...

. On 2 July 1941 ''Vesihiisi'', while patrolling east of Suursaari (

) 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 the besieged Soviet garrison at Hanko. According to Finnish sources, the convoy consisted of a transport vessel of the ''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 a group of

patrol boats A patrol boat (also referred to as a patrol craft, patrol ship, or patrol vessel) is a relatively small naval ship, naval vessel generally designed for Coastal defence and fortification, coastal defence, Border control, border security, or law ...

. According to Soviet sources, there were only four minor ships: the 489-ton freighter ''Hilde'', built in 1894, one T58-class minesweeper, and two MO-class patrol boats. The submarine penetrated the escort screen and launched two torpedoes at a range of while sailing 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 in 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 a 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 ( , ; ; ) is the capital of Åland, an autonomous territory under Finnish sovereignty. Mariehamn is the seat of the Government and Parliament of Åland, and 40% of the population of Åland live in the city. It is mostly surrounded b ...

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

Sea of Åland The Åland Sea (or the Sea of Åland; , ) is a waterway in the southern Gulf of Bothnia, between Åland and Sweden. It connects the Bothnian Sea with the Baltic Proper, Baltic Sea proper. The western part of the basin is in Swedish territorial w ...

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

Soviet The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...

S-class submarine , near

Lågskär Lågskär ( Swedish for "low skerry") is a small island within the Åland 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 me ...

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 (Lavansaari) and Seskar (Seiskari). The boat was attacked with depth charges by two Soviet minesweepers but was able to escape without any damage. The submarine laid a further 18 mines north of Moshchny Island on 6 July 1944.

Notes and references

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