Wolfgang Peterson's "Das Boot" The directors cut (1981)

This is a great film about WWII submarine warfare.  Never mind the fact that they were on the wrong side of the war in service to an evil regime.  Apart from the masters they served, they were merely men who were trying to do their best they could in a system they did not fully understand.  Like the American sailors in "From Here to Eternity", most of the enlisted men were scarcely men at all, but boys.  And their preoccupations were wine, women, and song before and after doing their highly unpleasant jobs is an example of  a universal of human nature at least in Western culture.  .  

Submariners of any nationality have long had to contend with the claustrophobic environment of the interior of their ship, and not much else. 

The sweat and stink of a crew of maybe 20 men who work in shifts cut off from sunlight and any sense of night and day.   And as increasingly becomes the case towards the end of the Second World War, the hunters were also the hunted, as increasingly sophisticated methods of anti-submarine warfare drew the noose tighter on the very ones who were trying to strangle the vital sea links between North America and Great Britain.  The fact is that of the approximately 40,000 sailors in the U-boat service for

Germany, only 10,000 survived the war.  Underwater locating technology and both sides, depth charges, and ASDIC (Sonar) fortunately evened the odds in favor of the Allies before the end of the war.   

There are some memorable scenes in this film, which swings continually from calm to horror/terror and back again.  In one scene they are surveying the burning wreck of an allied tanker, and assuming that the convoy would have picked up the survivors hours ago, they send in a torpedo as a coup de grace. 

It is only then that they discover that the survivors have not been rescued, and that by sending a gratuitous torpedo its way they have ensured that the survivors would not survive. And the scenes where they are desperately trying to fix the engines and the pumps while submerged, even resting on the bottom of the Strait of Gibraltar.   

I have no way of judging the "realism" of this film, other than it seemed plenty "real" to me:  the claustrophobia, the bad air, the

tight spaces, the dim light, the sounds of the metal plates of the ship creaking and snapping as the pressure of the water becomes greater and greater, even in the quieter moments when the captain put on various samples of his record collection for broadcast throughout the submarine.  As I have said, a great film and perhaps the greatest sub warfare film ever made.  Never mind that it was over 3 hours long in the director's cut, it was gripping from beginning to end.