When working on the true-life ship hijack drama Captain Phillips, director Paul Greengrass went after as much authenticity as possible.
The very first time actor Tom Hanks in the titular role saw the Somali non-actors playing pirates was during the filming of the scene in which the pirates stormed the ship.
To increase the tension in that key scene, Greengrass kept the Somali cast separated from the rest of his ensemble, so that when they met for the first time on screen, the uncertainty of the situation would play out with genuine, visceral emotion.
"It was extraordinary, actually," Hanks says of the explosive scene in which the pirates confront the captain with their firearms. "I was on the deck with a couple of the actors who were in the film, and we went through as human beings what the characters went through.
"We had never seen these guys before, but suddenly we heard the pirates coming, getting closer and closer, their guns firing. And then, when they finally came in and burst - I mean, literally burst - onto the bridge, we saw these living, breathing guys for the first time."
It was a frightening moment, the actor says. "They're the thinnest human beings you've ever seen, and they're incredibly scary because their heads are huge, their teeth are really bad, and they were waving automatic weapons and pistols at our faces and screaming at us."
The hair on the back of his neck stood on end, he adds. "It was a very, very emotional and visceral moment. We were truly petrified.
"Now, that being said," Hanks continues with a chuckle, "that only happened for the first take. By the third take, the Somalis were all smiles, saying, 'Hey man, I just want to say, I can't believe I'm working with a guy who played Forrest Gump.'"
Captain Phillips is about the 2009 Somali pirates' hijack of a US-flagged cargo ship, Maersk Alabama that was bound for Kenya with a 20-man crew.
As captain Richard Phillips, who was at the helm of the container ship, two-time Oscar-winner Hanks turns in a compelling performance, which The New York Times praises for being "unforced".
He says that he and the rest of the cast were required to "find our sea-legs very quickly", with 75 per cent of the 60-day shoot spent out on the open water.
"We shot this movie in Malta," he says, "and every day we went down to the port, got on the ship and that ship does roll when you're out at sea. I didn't have any real problems with sea-sickness and I don't think the crew did until we started working in the lifeboat."
The lifeboat scenes are very claustrophobic. "That was a very uncomfortable and unpleasant atmosphere to be in," Hanks says. "Basically, they stuck some guys in a lifeboat in the middle of the ocean and then went out and chased us with cameras.
"It was a pretty impressive array of run-and-gun film-making that went back to the days Paul Greengrass was shooting documentaries for the BBC.
"But all the cast and crew were up for the challenge because otherwise you're shooting a movie in a sound stage somewhere in LA and the biggest adventure you have is choosing which route to take to work. Playing in Captain Phillips was a great experience for all of us," says Hanks, who will be seen next as Walt Disney in the biographical drama Saving Mr.Banks.
"Every chance I've had, on movies like Apollo 13 and Saving Private Ryan, I am thinking of the best way to get people into the theatre and I think Captain Phillips is a very, very compelling story," he notes.
After the film was released in the United States, several members of the Alabama crew spoke out and cast doubt on the heroism of Phillips' actions, but Hanks spent time with the captain and was impressed by what he learnt.
"He is an incredibly pragmatic guy who went through something quite extraordinary and barely survived," he says of Phillips, who recorded his version of events in the book A Captain's Duty: Somali Pirates, Navy Seals, And Dangerous Days At Sea.
"And you know what he's doing right now?" asks Hanks. "He still goes out to sea for six weeks at a time. He is an absolute true merchant mariner who has great pride in what he does. I find that impressive."