German U-Boat Activity In Finnish Territorial Waters 1930's - 1940's



Very little information has been published regarding the German U-Boat activities in and around Finland in the year 1944. The following, attempts to describe this activity with information describing the Finnish submarine program and the subsequent involvement of German U-Boats in Finnish waters.

The Finnish Submarine Force

Between 1920 and 1921 the transitional German Navy became a permanent service once again and regular exercises and visits abroad were arranged. Though new construction was limited due to the high inflation rate then in progress, treaty evasion continued; orders were even placed for submarines to be built in Spain and Finland. The years from 1920 to 1924 marked the rebirth of the German Navy, but it was in the next period, from 1925 to 1932, that serious reconstruction was started. The building of U-boats abroad continued and crews for them were trained under the guise of receiving anti-submarine instruction.

....Following his rather unsuccessful negotiations with Argentina, Korvetten- kapitan Karl Bartenbach (former head of the U-Boat Flotilla in Flanders) had been Naval Adviser to Finland since 1924, and had taken pains to persuade the Finns to have submarines built to IvS (N.V. Ingenieurskaantor voor Sheepsbouw - Holland) designs. His initiative was rewarded in 1926, when the German Navy received a contract for 3 torpedo-armed minelaying submarines, similar to the IvS design for Pu89, to be built by the Crichton- Vulkan Shipyard at Abo (now Turku) in Finland. In contrast with the German UC boats of the First World War, the mines would be carried in wet storage, in shafts next to the pressure hull; this enabled submerged torpedo tubes to be fitted forward and aft. With this design, IvS achieved an operationally sound U-boat type, which greatly exceeded the Type UCIII in handling properties without requiring larger surface displacement.

The first boat, CV702 (Vetehinen), was laid down in September 1926. At the beginning of 1927, IvS sent three experienced U-boat builders, Hugo Peine, Wilhelm Etzbach and Edgar Rickmeier, to supervise work at Abo and, at about this time, CV703 (Vesihiisi) and CV704 (Iku-Turso) were laid down. The building time was very long — almost three and a half years. The yard's lack of experience, the difficult route for delivering materials, but above all the lengthy breaks during the very cold winter months meant that CV702 did not leave the slipway until 2 June 1930. CV703 followed on 2 August.
As before, IvS organized the trials through the Berlin U-Boat Office. On this occasion, as Abo was geographically very remote, the selection of personnel was not hampered by political considerations. As it seemed likely that this particular submarine type might have considerable significance for the future construction programme of German U-boats, Schottky himself took over direction of the crew, which included Papenberg as engineering officer and the active officers, Kapitanleutnant Karl Topp, Kapitanleutnant (Engineer) Karl Thannemann, and Oberleutnant zur See Hans Rudolf Rosing, and the retired officers, Leutnant zur See Plaas and Leutnant (Engineer) Lorek, plus the young designer, Watje, from IvS. As Topp and Thannemann had to leave the trials' crew for some time, Oberleutnant (Engineer) Bartel was later included. After a shakedown cruise of fourteen days (the crew, apart from Schottky and Papenberg, having had no experience of submarines), trials of CV702 began on 14 July 1930. In all essentials, they had been completed by 6 September 1930 and, at the conclusion of his report of them, Schottky claimed: "With regard to the diving qualities, the seaworthiness and the offensive abilities in relation to the displacement, Kapitan Bartenbach and I are of the opinion that these are better than any foreign submarines."

The "Lilliput" project:

Early in 1924, Finland had expressed interest in a small minelaying submarine, for which IvS, via Bartenbach, made a proposal (Pu23). The boat, of only 99 tons, had been designed by Hugo Seligmann, and was intended for special operations on Lake Ladoga. However, the Finnish Navy had been reluctant to give a decision, possibly because the boat was rather too small to serve as the nucleus for a Finnish submarine arm. During the following years, the offer was repeated in the form of Pu78/79, in connection with the larger design Pu89, but it was not until 1929 that Bartenbach succeeded in persuading the Finns to agree to the building of a small boat to an improved design, Pu109/110. She was built at Hietalahden Laivatelakka in Helsingfors, left the slipway on 2 July 1930, and was given her trials by Schottky's crew in the autumn of that year, together with CV702 and CV703. After her acceptance by the Finnish Navy, she was named "Saukko", and was the smallest submarine in the world at that time. She was launched 10 May 1933 and commissioned 13 January 1936.

"Vesikko" was ordered by a Dutch engineering company Ingenieurskantoor voor Scheepsbouw (IvS) in 1930 as a commercial submarine prototype. The construction of CV 707 begun in 1931 at the Crichton-Vulcan dock in Turku. After its construction, CV 707 became one of the most advanced submarine designs of its time. For example, the maximum depth was over twofold when compared to earlier German submarines, and its hull could be built completely by electric welding, without rivets – this increased resistance of water pressure, decreased oil leakages, and made the construction process faster. Germans tested CV 707 in the Archipelago of Turku during the years 1933–34. According to the agreement between the Finnish Ministry of Defence and the Crichton-Vulcan, Finland had the primary purchase option until 1937, and the Finnish Government took over the submarine during August 1934. After the Finnish Parliament had approved the acquisition in 1936, the submarine joined the Finnish Navy under the name of "Vesikko". "Vesikko" is a prototype for the German Type II submarines. Six Type IIA submarines (U-1 – U-6) which were almost identical to "Vesikko" were built in the Deutsche Werke dock in Kiel, and after these, 44 Type IIB, IIC, and IID submarines were built before and during World War II.

"Vetehinen", "Vesihiisi", "Iku-Turso" (3 minelaying submarines), and "Saukko" (small submarine) were sold to Belgium to be scrapped in 1953.
CV707 "Vesikko" (medium sized submarine) is now preserved as a museum at Susisaari Island in Suomenlinna, on the shores of the Artillery Bay, Finland. "Vesikko" opened as a museum on the anniversary of the Finnish Navy 9 July 1973.

 The Germans Make A Move...

The "Weddingen" Flotilla visits Helsinki

This port visit ocurred between 06-12 August 1937

(click on small images below to enlarge)

-- In The Port Of Helsinki --

Mooring in Helsingfors (Helsinki)

The Finns want to listen more music

The Finnish Admiral leaving the German tender "SAAR"

During the visit to Helsinki, there was a wreath-laying ceremony at the "Monument To The Fallen" - The "Memorial To The Fallen" in Helsinki

At the wreath laying ceremony - A delegation of the "Weddingen" Flotilla

Return from the wreath laying ceremony

Newspaper article/photograph showing U-Boats of the "Weddingen" Flotilla and the Tender "SAAR" at the rear and three Finnish Submarines forward


The "Badewanne" (Bath tub) U-Boats

In the middle of summer 1944 German submarines arrived to Gulf of Finland. Finnish and German submarines are employed in the inner part of the Gulf of Finland because of the critical situation in Karelia. The three large Finnish boats operate from the middle of June south of Koivisto and the two small boats near Tiurinsaari. "Vesihiisi" lays mine barrages near Peninsaari on 4 and 7 July; "Vetehinen" lays a mine barrage after two sorties into Koivisto Sound on 2 July and again on 5 July. "Iku-Turso" operates en route to Lavansaari (August), but, like "Vesikko" and "Saukko", has no success. The German boats that arrived in Finland were of type VII C. During June and July the German boats U 481 (23 June), U 748 (05 July) and U 1193 (24 June) arrived at Helsinki. During July seven more boats arrived (U 242 (17 July), U 250 (25 July), U 348 (18 July), U 370 (09 July), U 475 (07 July), U 479 (11 July) and U 679 (10 July) and in August three more boats arrived U 717 (19 August), U 745 (07 August) and U 1001 (08 August). The German submarine headquarters were located in Kotka under command of one of the most decorated submarine commanders, Fregattenkapitan Albrecht Brandi. The submarine commanders were in a totally different operational environment as usually. Instead of large, deep sea areas they now operated in confined, shallow waters ("Badewanne") infested with mines and light antisubmarine vessels. The operational areas of German boats were east from the Huovari-Narvi-Seiskari line and Narva Bay. The patrols lasted usually two days and no more than four boats were on patrol at the same time. They generally relieved each other every two days in the positions off Koivisto and in Narva Bay.

Some additional notes regarding Finland operations:

On 02 September 1944 Finland broke off diplomatic relations with Germany and sued for peace with Russia on 04 September 1944. From the 2nd the Germans evacuated their men, including the sick, and as much material as they could from Finnish harbors. Further U-Boat operations were carried out from Danzig, Gotenhafen and Memel. The loss of the use of Finnish harbors severely restricted U-Boat activities in the Baltic.

On 22 June 1941, when Nazi Germany invaded the Soviet Union, there were 218 submarines in the Red Navy, spread out among the Baltic, Black Sea, Arctic and Pacific Fleets.

.....The (German) Navy's insistence upon the defense of the Baltic Isles, like its earlier demands for holding the Leningrad and Narva sectors, resulted from Donitz's desire to preserve the mine barrages in the Gulf of Finland. The maintenance of minefields to blockade the Soviet fleet within the Gulf had constituted one of Donitz's chief goals in the Baltic since the very beginning of the Russian campaign. The effective use of mines was possible due to the geographic conditions of the Gulf, which has an average width of only thirty nautical miles. Shortly after the army had cut Leningrad's land link with the
Russian interior in September 1941, German and Finnish ships began to lay mines to seal off the Soviet fleet in Kronstadt Bay, although at this time the German Navy's, and Hitler's, greatest concern was that the Soviet fleet would break out and sail for neutral Sweden to be interned. Leningrad, however, held out, and the threat of the Baltic Fleet remained. In mid-April 1942 German and Finnish naval officers met in Helsinki to plan the establishment of mine barrages. This conference resulted in the decision to lay two minefields across the Gulf of Finland as soon as the ice melted: the Seeigel (sea urchin),
extending from the Finnish skerries, east of the islands of Tutters and Hogland, to Cape Kurgalowo; and the Nashom (rhinoceros), from Porkkala to the Estonian coast east of Reval. Several Soviet submarines managed to breach the mine barriers and operate in the Baltic in 1942, but they were unable to disrupt German shipping to a serious extent.
To prevent Soviet submarines from reaching the Baltic again, in the spring of 1943 the Germans supplemented their system of minefields by laying a double antisubmarine net, Walross (walrus), directly west of the Nashom mine barrage. This device proved a complete success, for no Russian submarines managed to break through to the Baltic until October 1944. Yet in the latter part of 1943 Soviet attempts to clear a passage through the southern portion of the Seeigel barrage alarmed the German Navy. In September 1943 Naval High Command, Baltic, reported a marked increase in Soviet minesweeping activity and warned that Russian air superiority made protection of the barrages by German patrol craft increasingly costly. Schmundt, Kummetz's predecessor, maintained that the forces at his disposal could no longer prevent Soviet vessels from clearing mines, due to their strong air cover.
Once the ice in the Gulf of Finland melted in the spring of 1944, the Germans replaced the antisubmarine nets and replenished the mine barrages, but once again the Soviet minesweepers set to work. Donitz ordered immediate attacks
against them, considering the use of destroyers for this purpose. In May the Soviets began to carry out fierce attacks on German vessels guarding the minefields. Swarms of Soviet aircraft attacked patrol vessels, inflicting serious losses. As a result, German submarines guarded the minefields by day, and surface vessels returned to protect the barrages under cover of darkness.
During the summer months, as Army Group Center collapsed and Germany considered the occupation of Finland's southern coast, the Ski examined all possible locations for minefields to continue the blockade of the Soviet fleet. Geographic conditions in the Gulf of Finland offered three possibilities. The first, and most desirable, was the site of the Seeigel barrage, the effectiveness of which had already been demonstrated. If this position could not be held, the next most favorable location was east of the Nashorn barrier, with a length of approximately thirty nautical miles. The third site was nearly forty-five nautical miles in length, from Dago's northern tip to Bengtskaer in Finland. Since the creation of this mine barrage required more mines than the navy had at its disposal, and because at this time the Ski doubted the army could provide troops to defend the Baltic Isles, Donitz rejected this location as impractical. The next day Hitler refused Army Group North's request to withdraw from Narva.
When the Soviets breached the Seeigel at the end of July, Burchardi requested that three submarines immediately take up positions in front of the gap until a new minefield could be laid. As the Nashorn minefield further west consisted only of antisubmarine mines, a breakthrough of the Seeigel would clear a path to the Baltic for Russian surface vessels. Donitz's greatest fear, that the Soviet fleet would enter the Baltic and disrupt German U-boat training, seemed close at hand. He requested the Luftwaffe to attack Soviet minesweeping units and protect German vessels laying new mines to close the gap. He also ordered Kummetz to send torpedo boats to guard the minefield, regardless of the danger from Soviet aircraft. Donitz's insistence upon maintaining patrols to protect the mine barrages resulted in heavy losses. At the beginning of August the operational strength of vessels assigned to guarding the minefields was less than one-third the number available the previous month. When the Germans retreated from Estonia, the navy lost its bases for the minefield patrols.
With the evacuation of Reval at the end of September the navy withdrew its surface forces guarding the minefields, although German submarines remained on patrol to protect the Nashorn mine barrage and the antisubmarine nets.....

The Germans, working in concert with the Finns, executed 103 minelaying operations to bottle up the Russian Baltic Fleet in the Leningrad/Kronstadt area. (Both sides made impressive and effective use of minefields.) German airpower was also very effective in the Baltic, in both offensive operations and anti-submarine warfare. Soviet submarines would occasionally break out of the minefields and elude the German anti-submarine flotillas, but with minimum effect. German naval vessels had escorted some 1,900 merchant ships, of an aggregate 5.6 million tons during 1942, and lost only 20 ships totaling 40,000 tons—less than one percent of the total.
The Soviet Union regained a presence in the Baltic in the late summer of 1944. The Red Army reached Riga in August, and the Finns surrendered on September 4. Hitler insisted that the remaining German bridgeheads in the Baltic be held as long as possible, but by the end of 1944 it was obvious that some 2,000,000 troops and refugees had to be evacuated from these areas.

Mr. Juhani Lievonen has written in the Finnish Journal of Military History 2008 an article ”The activity of German submarines in the waters near Finland in 1944-45” -(Juhani Lievonen: Saksalaisten sukellusveneiden toiminta Suomen lahivesilla vuosina 1944-45). The article is in Finnish, with a summary in English. for the complete article. The discussion of submarine bases in Finland is limited to the Summer of 1944.

In 1944 the German submarines were sent to Finland for two purposes: To encourage Finns after the major Soviet offensive that started in June and to monitor and attack Soviet naval forces. At first three boats were sent to a demonstation trip end of June. U 481 sailed from Tallinn to Helsinki 23.6, continued east to Kotka 25.6., did not stay there but sailed across Gulf of Finland west from Suursaari and to Tallinn 26.6. U 748 and U 1193 arrived in Helsinki 27.6. and made the same trip.

In the beginning of July it was not clear how many submarines should be sent to Finland and what would be their operational areas and targets. Finland had already its five submarines in the eastern Gulf of Finland and did not consider operations east from Suursaari barrage meaningful. When the Soviet offensive across Gulf of Vyborg started in the beginning of July, it was decided to station the German submarines to as far east as possible, close to the operating areas Trinidad north from Koivisto Sound and Bengalen east from Narvi island. The bases were mostly north and northeast from the Suursaari barrage. Some of them were also used by Finnish forces. The bases were selected so that there was a ready lane or deep water available and at least 5 m depth close to steep rocky shore for easy camouflage. It must be noted that the Soviet had almost total air superiority and submarines could operate surfaced only during nights. The operation of German submarines in the waters near Finland, which had begun in June 1944, ended on 17 March 1945 when the last boat, U 475, left the area.

The article lists the following bases/locations:

Referenced Geographical Areas - Finnish Bases And
Areas Utilized By German U-Boats






Stromelö, Finland 

  The island of Stormelö (Stormälä) also written as Stormalö, Stor Melö, Stromelo or Stor Malö in Parainen in the western Gulf of Finland, off Turku (60°15'14.88"N, 22° 8'30.49"E). This was used as temporary base by the Finns, and also by Germans.

Mössholm, Finland

  Or Myssholmen Island at 60°20'37 N, 26°27'34 E, east from Loviisa and north from the Myssholmsfarden open sea area. The base was on the east side of the island.

Busholm, Finland

  At 60 20.7 N 26 32.5 E. The name of the location suggests an island, but the place is in the south end of a chain of narrow roads. The place is on the opposite side of the Myssholmsfarden open sea area than the Mössholm base.

Oulu, Finland

  On the Northwest coast of Finland. 


Toppila, Finland 

  Near Oulu, Finland.


Korkiasaari Islands, Finland


(also known as Korkeussaari) - Are two islands, Korkeussaari and Pieni (small) Korkeussaari, halfway between Kotka and Hamina. The base with two anchoring places was on the north shore of Korkeussaari.

Nuokonsalmi (Nuokko Sound), Finland

Grand Hotel

Located at 60 27.5 N, 27 13.2 E, located between islands Sisa-Nuokko in the west, Riisiö-Majasaari north and Kalasiika (NW of Nuokko Island at AO 3265) east. Finns had built four piers in the sound. This was the main German base that was also closest to the operational areas. Up to five boats could be accomodated at the same time.

Risholmen and Bergholmen, Finland


Located at 60 22.3 N 26 08.4 E are two small islands north from western Keipsalo open sea area. The places were on west side of Risholmen and east side of Bergholmen. Finnish codename was Susi (Wolf).

Koukkusaaret, Finland


Located at 60 24.6 N 26 40.0 E, south from Keihassalmi Sound. The bases were on the east side of islands Lilla Krokö and Svartback Krokö. Krokö in Swedish is Koukkusaari in Finnish and Koukkusaaret is the plural form.

Hamnholmen, Finland 

  Located at 60 15.5 N 26 11.9 E, is an island southwest from Loviisa with direct access to open sea. There are two larger islands, Hamnholmen and Vastasaari, and the anchor place was on the south side of the Hamnholm. 


Altarskar Islands, Finland 

  Located at 60 18.2 N 26 15.4 E. The two islands Norra (Nort)(Nord) Altarskar and Södra Altarskar are located south from Loviisa and north from the Kofladan open sea area. The base was on the north side of Norra Altarskar. 


Koivisto, Finland

  Now called Primorsk, Leningrad Oblast, Russia (ceded from Finland to Russia in 1944).

Narva Bay, Estonia

  Located off Sillamäe and Narva-Jöesuu, Estonia at 59°25'54.73"N, 27°51'34.63"E

Byö Island, Finland

  (presently called Heinasaari or Angsön), north from Bisaballsfjarden open sea area. The two anchoring places were on the south shore of the island.

Hamina, Finland

  Located on the southern coast of Finland at approximately 80 km East of Helsinki.

Porkkala, Finland 

  Located on the southern coast of Finland at approximately 15 km South West of Helsinki.


Osel and Dägo Islands, Estonia

  Two islands off the western coast of Estonia.

Suursaari, Finland

  Gogland or Hogland (Suursaari) is an island in the Gulf of Finland in the eastern Baltic Sea, about 180 km west of Saint Petersburg and 35 km from the coast of Finland. Ceded to Russia at the end of the war.

 Notes: Map coordinate locations cited above can be found with Google Maps



German Grid Coordinates AG - AO


No 3100 Ostsee (Baltic) North


German Grid Coordinate Guide


German U-Boats Operating In And Around Finnish Territorial Waters

Listed below are the U-boats that operated in and around Finland during the period 1944-1945.

*The German (Type IID) U-boats listed below operated out of Stromelö and were initially or subsequently attached to the 22nd U-Flotilla at Gotenhafen after their "operational" duties ended. These boats were used for actual operational duties during the initial stages of the war with Russia. Their "operational" dates that they were employed for patrol duties are noted for each boat* below.

German U-boats also operated with Finnish submarines in training exercises between 03 and 15 July 1943 in the Gulf Of Finland.

Boat No.


Operational Area(s)


Operational Area Map

Op. Area(s) Marine Grid

Operational Log

Amplifying Notes


U 139*





U 142*






von Mittelstaedt









U 242




U 250





U 348





U 370





U 475




U 479






U 481





U 637






U 676






U 679



U 717

von Rothkirch und Panthen


U 745

von Trotha





U 748



U 958



U 1000



U 1001



U 1165


"Ratte"  ---        

U 1193


  ---       23 August 1944 receipt of orders to go to from Helsinki to Libau

For additional information regarding the operations of the Finnish Navy - Consult the
Finnish "War Diary" for April - December 1944 here

The remaining Finnish "War Diary" entries are located here  

Some additional comments from Jari Aromaa:

The navigation to Nuokko Sound was not easy and there were several incidents when boats ran aground. My grandfather (Lt. Tauno Paukku) was sent there 8. July with the task to pilot the German boats to and from the base. The plan was that he should change from outgoing boat to incoming, but at least once this could not be done and he was in the German boat the whole patrol.

Many of the people living on the Finnish coast were Swedish speaking. Mr. Lievonen mentions in his article that Swedish Naval officers as well as Finnish Naval officers were also working as pilots, but I do not know their names.

The last boats in the temporary bases were three boats in Grand Hotel and two in Miramare on 02 September 1944. When these boats departed they did not return to Finnish bases but sailed to Estonian harbours Tallinn, Kopli and Paldiski.

Many thanks to Jari for all his inputs........


Many thanks to Jari Aromaa (Finnish Navy in World War II History) for providing much of this pertinent info... 


References - Bibliography:

Kurzfassung Kriegstagesbuecher Deutscher U-Boote 1939- 1945, Band 1-14" by Herbert Ritschel
U-Boats at War: Landings on Hostile Shores by Jak P. Mallmann Showell (2001) - ISBN 978-1557508645
Der Seekrieg in den osteuropaischen Gewassern 1941-1945 by Jurg Meister (1958) Munich, Germany
U-Boat by Eberhard Rossler (2001) - ISBN 0-304-36120-8
Chronology Of The War At Sea 1939-1945 by Jurgen Rohwer (2005) - ISBN 1-59114-119-2
Hitler, Donitz, and the Baltic Sea: The Third Reich's Last Hope, 1944-1945 by David Grier - ISBN 978-1-59114-345-1
U-boat Operations of the Second World War: Volume 1: Career Histories, U 1-U 510 by Kenneth Wynn (1998) - ISBN 978-1557508607
U-Boat Operations of the Second World War, Vol. 2: Career Histories, U 511-UIT 25 by Kenneth Wynn (1998) - ISBN 978-557508621
Military History Magazine No. 27, 2008 "Juhani Lievonen: "German submarine activity in the waters close to Finland in 1944-45" - (Juhani Lievonen: Saksalaisten sukellusveneiden toiminta Suomen la"hivesilla" vuosina 1944-45) - (information forwarded by Jari Aromaa)
Finnish Navy in World War II
Forum Marine Archiv
Axis History Forum
Photo collection of S. Mata
Unterseebootsbegleitschiff und Flottentender "SAAR"
German Marine Grid Converter

I would welcome any additional info or corrections regarding

the information presented - They may be submitted to -

Ken Deshaies - Newton, New Hampshire - 2014