Bryan Alexander | USA TODAY

USA TODAY

SOMEWHERE OFF THE COAST OF SAN DIEGO – “Prepare to dive,” the officer of the deck barks into the USS Annapolis' PA system.

It's game-face time.

U.S. NAVY/MC1 RONALD GUTRIDGE

On a sunny San Diego morning, the training exercise has embarked on calm seas off Naval Base Point Loma, where the nuclear-powered fast-attack submarine is stationed. But it's all serious for the officers and crew onboard, who are intently watching digital navigational screens throughout the control room.

Submerging on a submarine, particularly one capable of carrying torpedoes and 12 Tomahawk land-attack missiles, is a vulnerable time that requires unwavering vigilance.

Two periscope operators scan the 360-degree water surface, spinning in a perfectly synchronized dance mere feet apart, somehow avoiding collision, as the officer in charge of the ship's movement gives commands to the sonar operators in a separate room.



“Dive! Dive!” the chief of the watch orders, sounding two blasts of the diving alarm before switching open the ship’s main ballast tank vents to let seawater in. The 6,900-ton war machine slips beneath the choppy surface and glides underwater effortlessly.

Even behind his facial stubble, “Hunter Killer” director Donovan Marsh cannot hide an amazed smile as a rare civilian (along with a USA TODAY reporter) witnessing a highly classified nuclear submarine in full operation. Unlike his first visit on a fast-attack sub before filming began, Marsh is now able to breathe easier knowing that his nuclear submarine thriller starring Gerard Butler is completed and headed to theaters on Friday.

JACK ENGLISH/LIONSGATE

He acknowledges being slightly overwhelmed when he observed a sub at work before starting "Hunter Killer."

“I can remember watching all this and just thinking, ‘How am I going to bring this to the screen and do justice to the complexity of the way the submarine works?’ And knowing that I could not build an entire submarine. There was a lot of anxiety,” he says. “This war machine is an awesome, and frightening, scene to behold. It’s just an incredible piece of technology.”

The high-tech underwater world is the uncredited star of “Hunter Killer,” with Butler playing Captain Joe Glass, who takes his deep-diving sub – built to hunt and destroy enemy vessels – beneath the Arctic Circle to thwart a destabilizing Russian military coup.

It's pure popcorn Hollywood fiction, but it's based on the novel “Firing Point,” written by George Wallace, retired commander of the nuclear attack submarine USS Houston, and Don Keith.

Marsh knew he would need to create a realistic environment within the film. Before starting production, Butler (the actor, a producer on the film, wasn't able to make the latest sub excursion) and Marsh spent three days observing and bunking on the USS Houston. There were moments of pure exhilaration, such as bidding a long farewell to the base at Pearl Harbor, Hawaii, from the ship's open-air bridge with celebratory cigars.

U.S. NAVY

“That’s the first thing you experience on a sub, three hours just watching as you leave the port,” says Butler, speaking later by phone. “That feeling is incredibly powerful, unforgettable and exciting.”

But the work trip, during which Marsh slept in berthing quarters with the crew, persuaded the director that he needed to place the film’s entire set on a massive hydraulic gimbal to capture realistic movement – and that more Navy help was needed to tell the story.

The U.S. Department of Defense granted Marsh two days aboard another nuclear sub to shoot scenes with actual submariners to be worked into the fictional dramatic footage, showing the crew performing fire drills and being rousted from crowded bunks. A stand-in for Butler was filmed dramatically sliding down the ship's ladder past “millions of pipes and wires."

"It’s such a great shot," says Marsh, who marvels at the intricate inner workings crammed into a few hundred feet of HY-80 steel. "But it would have been impossible to build all of this for one shot.”

Marsh attached cameras to the ship's sides to film the vessel submerging and used the base’s “wet-trainer” room, where sailors get hands-on damage-control experience, to shoot scenes of lethal flooding. The dramatic capper was capturing a submarine making an “emergency blow,” or dramatic rise to the surface.

That shot was tricky. One take only, and Marsh, in a helicopter, wasn't given the coordinates of the rising sub. That was "classified."

LIONSGATE

“Luckily, it came up just in the corner of the shot and we caught it," he says.

Even for civilians on the Annapolis day trip, the “classified” aspect looms large on a vessel with the nation's top military technology. Mobile phones and cameras are collected (photographs are provided by the Navy after official clearance to make sure no secrets are given away). Minders are present at all times, and the nuclear reactor section is absolutely off limits. Questions as simple as speed or distance traveled are answered with a polite "That's classified."

But Marsh is granted a full tour of the ship (minus the nuclear reactor), from the torpedo room (where he pulls the trigger on a torpedo tube filled with water) to the 90-square-foot food galley (which maximizes all space impressively to feed the 137-man crew).

The food is a major perk, with lobster and steak dinners and pizza nights as celebrated high points. It's key for morale in a tightly confined sub that's capable of staying underwater for 90 days.

“And the captain eats just like any other seaman. It signifies that we are all in this together,” says visiting Capt. Christopher Cavanaugh, commodore of Submarine Squadron 11, during the tour.

U.S. NAVY/MC1 GUTRIDGE

The Navy received no payment for the "Hunter Killer" filming, and officials stress there’s no cost to the taxpayer, as the film crew joins active drills and exercises already underway. But shooting a movie like "Hunter Killer" is a big public relations boon, portraying the drama and potential excitement of the undersea world.

“They desperately need people to join the submarine crew, and being in this kind of enclosed space is not to everyone’s taste,” Marsh says. “Putting this onscreen can be seen as a recruitment tool.”

Navy officials encouraged Marsh's decision to add a female crewmember aboard "Hunter Killer": Women have been allowed in the fighting force only since 2010, and there are no female crewmembers on the Annapolis. "It's the future and a great addition to the film," Marsh says.

The director is treated to a hamburger lunch in the wardroom, the traditional officers' mess, on a table that would serve as a surgery platform in an underwater emergency. "Silent service" signs on the doors remind that they should be closed quietly to avoid vibrations that could be detected by enemy sonar.

U.S. NAVY/MC1 RONALD GUTRIDGE

After burgers and vanilla ice cream, Marsh is granted the ship’s honorary pin by the submarine's commander John C. Witte, who tells him, “Thank you for what you’ve done. And I can’t wait to see the movie.”

As the Annapolis comes to surface for its return to base, Marsh takes in the final scenery from the bridge. Incongruously, a pod of dolphins appears along the crashing wake of the ship's starboard side. They jump happily in the air alongside the war machine.

The director gets contemplative about the world he's about to reveal in theaters.

"One day these men are going to go out there and maybe die. That’s what kind of keeps coming back to me. But you also think, what an incredible experience. And an honor to depict these people even in a make-believe world."