After a first act that is mostly in German with English subtitles, leading into long exposition scenes that take forever, “U-571” turns into one heck of a taut, exciting action film with surprising depth (get it? It’s about a submarine!) and emotion.

It’s 1942, and a German submarine, U-571, has been wrecked by the Americans. A Navy crew led by Capt. Dahlgren (Bill Paxton, looking very Tim Robbinsy) is dispatched to sneak onto the disabled sub and find the “Engima” — an encryption device that, once in the hands of the Allies, will enable them to understand the codes the Germans use to communicate with each other. (This is based loosely on true accounts of this sort of daring thing happening in World War II.)

The plan is to show up dressed like the Germans, accompanied by two U.S. soldiers who speak German, and infiltrate the sub by pretending to be bringing supplies. Things go awry, though, when a German destroyer blows up the American’s ship while most of them are on board U-571 — leaving them stranded on a non-functioning submarine that will soon be rescued by Germans, who no doubt will not take kindly to finding Americans on their U-boat.

In compliance with action-movie genericism laws, Lt. Andrew Tyler (Matthew McConaughey) is told early on that he’s not good enough to command a ship; naturally, within moments, he finds himself at the command of a ship. Also, in order to prove Americans aren’t the cold-blooded killers Germans are, the guys take a German fellow as a prisoner, rather than killing him, thus enabling him to screw up their plans more than once before someone finally has the sense to kill him — but even then, he doesn’t like doing it.

There’s also a whole lot of submarine talk, with people yelling things pretty much randomly: “Everything’s in German!” “I can’t find the valve!” “Torpedoes in the water!” “Everyone’s yelling!” “No one’s listening!” “Batten down the hatches!”

But there’s also some major suspense and action, and an inspiring theme of loyalty, courage and patriotism, nicely written and directed by Jonathan Mostow. Notice especially Chief Klough (Harvey Keitel), a man much older than Tyler who nonetheless remains completely loyal to him as a commanding officer.

Pay attention also to Rabbit (Will Estes) and Trigger (Tom Guiry), young recruits who devotedly (though with terror always in their eyes) obey every command with exactness. Rabbit’s response to the death and subsequent dispatching of his friend, the rebellious Mazzola (Erik Palladino), is especially touching, as is Trigger’s human and realistic reaction to a mission he doesn’t think he’s capable of filling.

Aside from being entertained and thrilled (check out the spectacular sea explosions), one also gains a strong sense of pride and gratitude for the men who actually fought this war, who bravely did the stupidest things imaginable in the name of freedom. As the film’s tagline says, heroes really are just everyday people who act courageously in extraordinary circumstances.

A- (1 hr., 56 min.; PG-13, semi-frequent profanity, lots of explosions, some hand-to-hand combat resulting in some blood and death.)

In 2012, I reconsidered this movie for my Re-Views column at Film.com.