Operating under the Ice

Kriegsmarine U-boats Operating within or under the Ice

On 23 July 1958 the first nuclear powered submarine of the US Navy USS Nautilus (SSN 571), commissioned on 30 September 1954, left the US Naval Base of Pearl Harbor in Hawaii for an enterprise not dared before: As the first submarine ever to sail submerged from the Pacific Ocean to the Atlantic Ocean via the Arctic, including passing the North Pole under water. On 01 August 1958 the Nautilus submerged off Point Barrow in Alaska, to reach the North Pole on 03 August 1958 at 23.15 hrs, transmitting the famous radio message “Nautilus 90 degrees North”. Some 96 hours and 1.830 nm later the submarine surfaced again on 05 August 1958 between Greenland and the Svalboard Islands, to arrive at the Royal Naval Base of Portland, England on 12 August 1958. With that, the first documented voyage of a submarine under water and under a compact layer of ice had been achieved, which in the time to come has become a routine maneuver for nuclear powered submarines of the US Navy, the Royal Navy and the former Soviet and today´s Russian Navy.

As a matter of fact, extended maneuvers submerged under a compact layer of ice by submarine have been executed before. There are a few cases of Kriegsmarine U-Boats documented where these had to dive under compact ice formations for more or less operational requirements in order to pass sea areas blocked by ice. Also, cases became known through pictures where Kriegsmarine U-Boats became icebound within coastal waters or where they allowed themselves to be caught in firm ice fields to enable offloading of personnel or material and shifting it to shore nearby across the frozen sea.

Sources and literature mentioning such cases are rare. In some publications the usual problem can be observed that narrations after superficial research of German U-Boats operating in frozen sea areas or even under layers of ice have been taken for granted without thorough scrutinizing, and even transforming those to rather imaginative presentations. And, not unexpectedly, some myths have developed from that. It is, therefore, imperative to at least study the war diaries of the appropriate higher commands of the U-Boats in question, to verify whether there have been actually events of underwater passages of ice fields or longer lasting icebound situations near to coasts allowing offloading of personnel or material onto load carrying ice layers. Also, errors excepted tales by eyewitnesses may help, if supported through reports by others, ideally, however, if confirmed by proven historic events.

We have done this at the U-boat Archive, and we would like to present three confirmed cases we have found during our research of Kriegsmarine U-Boats having operated in the frozen sea. Another fourth case one can spot in literature can only be assessed as fiction and not proven by any sources.

Intentional icebound situations close to shore

U 377 within closed ice field in Signe Bay at Svalbord Islands
U 377 within closed ice field in Signe Bay at Svalbord Islands

30 Oct to 07 Nov 1942 at the Svalbord Islands: U-377

After the U-boat had delivered the unmanned weather station WFL 21 “Gustav” at Ny Ålesund at Western Svalbord between 06 and 08 September 1941 and embarked the first group of 4 men of the weather commando “Nußbaum” at Narvik and Tromsö the commando was transported to the former location of the weather commando “Knospe” at Svalbord (see: U 435), to be followed by reconnaissance of the Northwestern coast of Svalboard. Pictures taken from the second transport operation of remaining material for “Nußbaum” plus 3 more weather observer specialists following the departure from Narvik on 27 October 1942 show that U 377 had allowed itself to be frozen in entirely by the ice covered sea in the Signe Bay of the Kross Fjord. So, between 30 October and 08 November 1942 U 377 was able to unload personnel and material directly from the boat to the ice, to be transported further by means of sledges to shore.

An extract from the war diary for the combat patrol 25 September to 25 November 1942 reads as follows:

30 Oct/ 15.38 – Have proceeded with slow speed right into the field of unruffled ice in the bay. Boat is stuck.
Nielsept: 134 °
Frodtjovneset: 30°

And, the further summary report reads as follows:

31 October to 07 November – Offloading and transport of further equipment. Until 03 November work could be executed relatively smooth, but then it was hampered significantly by thaw and strong embacle…

On 08 November 1942 at 09.47 hrs it was “weigh anchor” and U 377 departed the bay, to reach Harstad, Norway on 12 November 1942.

Underwater passages of compact fields of ice:


U 435 during evacuation operation for weather commando "Knospe"
U 435 during evacuation operation for weather commando “Knospe”

26 August 1942 near  Svalbord: U 435

While in combat mission against Arctic convoys U 435 was retasked on 22 August 1942 to evacuate in a special mission the 6 men strong weather commando “Knopse” (= bud) from the end of the Kross Fjord at the Western coast of the Western Island of Svalbord, which had be brought there on 15 October 1941 by the weather observer vessels Sachsen and Fritz Homann. The embarkation of the commando and parts of its material occurred on 24 August 1942, and on 19.45 hrs that day it was “weigh anchor”. The Commanding Officer decided, to continue his ice reconnaissance on the return leg to Norway through passing north and east of the Svalbord Island, at some time the U-boat even passed the 81 degrees latitude. Northeast of the island of Kvitøya, which is located east of the Northeastern island of Svalbord, U 435 met on 26 August 1942 an extended and closed barrier of drift ice of estimated having a width of some 1,500 meters. U 435 submerged and passed the ice field under water during the next 30 minutes.

The war diary for this event reads as follows:

26 August/ 07.28 – Boat submerged to dive under a firm barrier of drift ice of about….1,500 meters wide, stretching from North to South from horizon to horizon…
26 August/ 07.58 – Boat surfaced.

With that passage under an ice field U 435 is one of the first U-boat in history that has deliberately dived under a layer of ice not known to full extend to continue its intended course, although other than initially planned. In literature this demanding seamanship and navigational maneuver is presented by some authors misplaced by claiming that U 435 is to have passed under the frozen Hinlopen Strait separating the Northeast and West Island of Svalbord for a longer time. The war diary clearly says differently, but even we in the U-boat archive believed that myth for a long time as proven.

02 May 1943 in Labrador: U-262

After U 262 had left its base at La Pallice, France on 06 April 1943 it received on 15 April 1943 the order to carry out a special mission, which was to evacuate German Naval PoWs at North Point at the northern tip of Prince Edward Island in Canada. The PoWs shall have made it to that point of contact by that time after having escaped from the PoW Camp No. 30 at Fredericton in Prince Edward Island in a secret operation (Operation “Elster” = Magpie). In order to reach the planned point of embarkation at North Point the U-boat had to pass the 60 nm wide Cabot Strait between the big Canadian islands of Nova Scotia and Newfoundland.


U-262 in La Pallice
U 262 at La Pallice

U 262 managed to reach the rendevouz point on 02 May 1943, but had to break off the mission on 06 May 1943 without any success because the intended escape operation apparently had failed. While proceeding towards the meeting point U 262 encountered a barrier of completely closed drift ice. The Commanding Officer decided to dive under the ice field, although he just maintained nothing more than hope that he might reach ice-free water later on his way, to surface again there. In the end the underwater voyage lasted an amazing 16.03 hrs before the U-boat was able to surface again, only after a second attempt to do so. When returning from the assigned point of embarkation after 06 May 1943 the U-boat was able to pass the Cabot Strait without any requirement to dive under ice.

The entries to the war diary of this remarkable passage under the ice read as follows:

27 April/ 08.04 – Both engines Full Speed. Am in the Cabot Strait.
27 April/ 08.20 – Both engines Slow Speed. Ice field ahead, drift ice and sliding ice. The field is much larger and dense than the previously noted. Passed the ice field with engines Dead Slow. The ice fields grow permanently in terms of size and depth, which find me stuck in an immense field of drift ice. I assume that more to the west the ice will further close to a solid layer of ice. If this is the case I will be forced to abandon my mission. Notwithstanding the compact mass of ice I decide to sail under water in northwesterly direction. I hope that I will have passed the ice field submerged when surfacing in the evening, which, perhaps, may just block the exit of the Cabot Strait.
27 April/ 10.12 – Have dived in a hole of open ice-free water with engines at stop.
28 April/ 02.15 – Surfaced. Attempt to surface. The hatch in the conning tower cannot be opened due to an ice -floe laying on top
28 April/ 02.20 – Surfaced. Second attempt. The hatch in the conning tower can be opened with great difficulty, the railing at the aft conning tower as well as the port net cutter ripped off, gun and MG C 30 damaged, outside doors of torpedo tubes No. I, III, and IV cannot be opened, anything bend by ice. 300 meters ahead I have ice free water.

Demonstrably this is the longest passage of a U-boat under a closed and unexplored layer of ice so far, showing a remarkable level of daring as well as great seamanship and navigational skill. Also, in literature some authors present this voyage under the ice as having lasted 18 hours, what can be read correctly in the war diary to have been still an amazing 16 hours. Notwithstanding, the achievement of the crew of U 262 is an outstanding event.

Allegedly: U-514 in the St. Lawrence River on 13 Sep 1944

In literature one also can find the story of another passage under the ice by a German U-boat, i.e. U 541 at the entrance to the St. Lawrence River in Canada, where this snorkel U-boat, after having left Lorient on 06 August 1944, was tasked together with U 802 to attack Allied shipping. Indeed, U 541 was successful in sinking the British freighter Livingston northeast of Nova Scotia on 02 September 1944. However, reading the war diary and other primary sources, there is no mentioning of the alleged diving under the ice at the approaches to the St. Lawrence River as of 13 September 1944, followed by surfacing somewhat later within the ice field to reload its batteries.

The U-Boat´s war diary for 13 September 1944 reads rather uneventful (Note: The position reports on the 13 September 1944 are stated to be BA 35 and later BA 38, which were the entrance to the St. Lawrence River as decoded by the Kriegsmarine Quadrant System):

13 September/ 01.36 -Begin of snorkel patrol
13 September/ 02.54 – Light of Gt. Cawee true bearing 313 degrees, repeated every 10 sec, no change
13 September/ 05.50 – Beach of Trinity in sigth in bright light
13 September/ 06.04 – End of snorkel patrol, light of Pte. des Monts true bearing 232 degrees, no change
13 September/ 09.15 – Weak hydrophone bearing starboard ahead 55 degrees, true bearing 279 degrees, 120 rotations per minute, moves further ahead, disappears after a quarter of an hour in true bearing 255 degrees
13 September/ 09.42 – Begin of snorkel patrol
13 September/ 11.13 – End of snorkel patrol
13 September/ 12.00 – Day´s run: Under water 63,0 nm
13 September/ 16.26 – Weak hydrophone bearing starboard ahead 30 degree, true bearing 208 degrees. Nothing seen at periscope depth. Nothing heard any longer after 10 minutes.
13 September/ 16.50 – Have stopped at water layer at 30 meters to save power and to improve listening capability

There are no entries about embacle or diving maneuvers under the ice, neither for the days within the St. Lawrence River nor before and after that. We also read the memories of the Commanding Officer of U 541, Kapitänleutnant (= Lieutenant Commander) Kurt Petersen about this patrol, when he decribes the patrol of his U-boat in the inner St.Lawrence River between 12 September/ 09.35 hrs and 16 September/ 03.04 hrs without mentioned any encounter with embacle. With that, this U-boat cannot be counted as another example of a maneuver of a German U-boat in or under a closed layer of ice.


There may be further cases of events not researched yet where Kriegsmarine U-Boats due to operational requirements have let themselves to be frozen in firm ice fields or have dared to dive under the ice. In the bizarre world of conspiracy theories there are, quite naturally, stories about bold operations of German U-Boats in the ice of the Arctic, and even of Antarctica, which manures the ground for many myths until today.

The few cases of actual events where U-Boats let themselves to be frozen in or did dive under the ice are the result of individual decisions by the Commanding Officers at the scene. These were not operations in execution of orders by Higher Commands to penetrate the ice. Just the opposite: Many messages show clear directives of higher authorities to avoid or evade ice fields. Reasons for that are the experiences gained by U-Boats from icing situations in their homebases in the Baltic Sea and Norway as well as during patrols in the Arctic Seas and close to the Arctic Islands. U 262 describes in detail the damages inflicted to the boat after its bold submerged patrol under the ice of the Canadian coast.

It remains to be said that there has been at least one case of a submarine having sailed under the ice for a longer period of time executed by a German U-boat in World War II, well before USS Nautilus did based on her rather different technical capabilities in 1958.

War diaries of BdU and U 262, U 435, U 377, U 514


  • Hadley, Michael, U-Boats against Canada, University of Toronto Press, 1990
  • Nusser, Franz: Die Arktisunternehmen des deutschen Marinewetterdienstes in den Jahren 1940-1945, Deutscher Wetterdienst, Hamburg 1979
  • Mallmann-Showell, Jak: U-Boats at War II – Landing on Hostile Shores, Ian Allan Publishing Ltd., Shepperton 2000
  • Selinger, Franz: Von Nanok bis Eismitte – Meteorologische Unternehmungen in der Arktis 1940-1945. Convent Verlag, Hamburg 2001, ISBN 3-934613-12-8

Text: Peter Monte – Pictures: Deutsches U-Boot-Museum