Submarine X-1 (1968)

If you remember "Above us the Waves" (1955) you'll get the gist of this story for James Caan. He's "Bolton", a man with plenty to prove to his superiors and himself after a tragedy struck a previous command. He's a bit of a slave driver, and that doesn't make him popular amongst his crews who find themselves training more and more aboard their tiny submarines on a remote Scottish loch. A raid by some Nazi paratroopers makes them realise, though, that their operations are now on the enemy radar, so expediency kicks in and their mission announced. They are to sail to the steep-sided fjords of Norway and there attack a powerful enemy ship that's been raiding the transatlantic convoys. It's all highly experimental stuff, but can "Bolton" and his highly trained sailors manage to hit their target? It's all fairly standard fayre, this, but it's still quite entertaining - especially in their glorified sardine cans being tossed about in heavy seas, avoiding nets and mines and their own claustrophobia. Caan does enough to keep it moving, and there is enough for the supporting cast of malcontents - an unremarkable collection of B-list British regulars - to set up the full effect of the denouement, but I doubt you'll remember it for long.