I saw this film when it was released in the mid 1960s, again on VHS over the years and finally on satelite television. It holds up very well. The theme of obsession in the line of duty is as relevant today as it was when Melville wrote "Moby Dick". The acting is excellent. Hats off to Eric Portman as the West German Navy commodore advisor in submarine warfare. He sort of reprises his roles in the "49th Parallel" and "We Dive at Dawn". He is one Englishman who portrays a great German. Martin Balsam does his usual excellent work as the under appreciated ship's doctor. This also contains yet another of Sydney Poitier's race neutral rolls. Very revolutionary for the mid 1960s ("Lillies of the Field" being another).
The ship model and iceberg scenes seem a bit dated in this digital graphics era but I shudder with cold every time I there is an exterior scene. I sailed in Greenland waters once and I know what is feels like on that grey ocean under that grey sky.
Clearly, this is British production. One interior shot of the ship shows a rack of Enfield rifles, already obsolete by the time this film was made. Not a problem really.
The suspense and tesnion hold up well after several viewings and the inevitable ending is, well, inevitable.
If you did not grow up during the Cold War this film will have less impact than living with the bomb ("The bomb, Alexi, the Hydrogen bomb..." oh, that was another cold war film).