Director Donovan Marsh on How the Navy Helped Make 'Hunter Killer'

The submarine thriller "Hunter Killer" (out now on 4K UHD, Blu-ray, DVD and Digital) had a long and complicated journey from book to screen.

Based on the novel "Firing Point" by Navy veteran George Wallace and Don Keith, the Gerard Butler movie was days away from beginning production when Relativity Studios shut down.

After a delay, new director Donovan Marsh joined the project. They regrouped with Summit and made a movie with extensive support from the Pentagon, which envisioned the film as a "Top Gun" for submariners.

Gerard plays Capt. Joe Glass, a maverick who is given command of a sub even though he didn't go to Annapolis. The Russian president gets kidnapped, and Glass must break the rules to save the world.

"Hunter Killer" features an impressive cast that includes Gary Oldman, Common, Linda Cardellini, Toby Stephens and Michael Nyqvist from the original Swedish Lisbeth Salander/Millennium movies

Marsh made the well-regarded South African crime thriller "Avenged," but "Hunter Killer" is his first big Hollywood movie. He told us about working with the Pentagon, how much of the movie was shot on real submarines, and how you make an action movie on a submarine.

You're from South Africa, a country not known for its Navy. Did you have an interest in military movies or history growing up?

South Africa has two diesel submarines, but only crew for one. One is in dry dock, and they can't afford to take the other one out. So if I couldn't love my own Navy, I could love the navies of the movies. Enter "Das Boot," "Crimson Tide" and "Hunt for Red October." Three of my favorite films of all time.

Gerard Butler worked on this movie as a producer for many years before it got made. Tell us how you came on board as the director.

The film had a different director and was months from shooting with Relativity. When Relativity came apart, the film was looking for a new home and a new director. I pitched and won the job. When I came on board, Gerard, Oldman and Common were already part of the project.

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• US Navy Vet George Wallace Wrote the Book That Inspired the Movie 'Hunter Killer'

The Pentagon has been unusually supportive of your "Hunter Killer," even hosting a press conference with Gerard Butler. What was it like working with the Navy on the movie? Did they have input into the filming since they gave your production so much access to Navy subs?

The Navy was incredible. They welcomed us in Pearl Harbor, sent myself and Gerry out on a real nuclear sub for three days, and showed us behind the scenes in the way that few civilians ever get to see. They gave us access to Navy experts, captains and admirals every step of the way, many of whom were present during filming and who made sure we stayed as realistic as was dramatically possible (and without giving away anything classified!).

The submariners want to know. How much filming did you get to do on real submarines and how much did you recreate on sets?

I had one day in the USS Texas with the real crew They were amazing; I challenge you to pick them out from the actors. I had one afternoon with the Texas at sea for helicopter shots. We nearly crashed the chopper (metal in the transmission!), had to return the next morning to shoot the emergency blow. I had one take and only knew the point they were going to surface within 100 hundred meters. They surfaced in the edge of shot and I quickly reframed!

What roles did practical and CGI effects play in your production?

We had 900+ visual effects shots that took over a year to complete. It was the biggest challenge of my life, and I still feel they could have been much better. To simulate reality is very difficult, and only the most skilled VFX teams with months and months of time can do it.

A submarine commander once told me, "The Army plays rugby. I play chess." How do you approach a battle movie when you've got to depend more on suspense than brute action?

I just flat out prefer suspense to brute action. It's more interesting. It's delicious. It's dramatic. During brute action scenes, I always end up looking at my watch. I wanted HK to create as much tension and suspense as the audience could bear and then release that with action that was quick, sharp and believable.

Even though the movie portrays American and Russian presidents who are nothing like the real leaders, "Hunter Killer" portrays a contentious relationship between the two countries that didn't exist even five years ago. Did rising tensions between the U.S. and Russia help you get this movie made?

Tensions between the U.S. and Russian escalated leading up to this film, significantly adding to its relevance. A Russian MiG buzzed a destroyer, and Russian sub activity in American waters and vice versa was on the rise. This played in wonderfully to the plot of the film, which starts with two subs getting into it under the ice.