Erik Skjoldbjærg shot his 1997 thriller Insomnia in the midnight sun above the Arctic Circle. Now, the Norwegian is going deep underwater in his new thriller Pioneer [pictured], sold by Trustnordisk and now in post-production.

The film is set in the early 80s, the height of the so-called Norwegian “oil boom” of the 1980s, when Norway began to cast off its underdog status and to emerge as a major economic power. Its lead characters are divers (played by Aksel Hennie and US actor Wes Bentley) venturing deep down beneath the ocean’s surface.

Appropriately enough, Skjoldbjærg and Hennie were in Cannes on Saturday, the wettest day in the festival’s recent history when the Croisette itself was under water.

“This film consists of tiny, claustrophobic spaces..and of infinite spaces,” Skjoldbjærg says of his film. “The biggest challenge was the underwater stuff.”

Much of the underwater shooting was done in Iceland at night time, close to a glacier where the water is filtered by lava sand and is, as the director says, “supposedly the clearest in the world”.

Pioneer may be fictional but its characters are based on real-life prototypes. During the oil boom, top American divers came to Norway to help the local divers to go more than 400 metres below the surface. The divers were alpha male types, intensely competitive with one another and desperate to be the first one to break new barriers.

“The Americans knew more than the Norwegians at that time. They had a lot of knowledge we didn’t have,” the actor states.

Yes, Hennie says, the water was absolutely freezing. The actor (best known for Headhunters and Max Manus) is already an experienced recreational diver. For Pioneer, though, he had to push himself to new limits, wearing huge, unwieldy diving suits and big helmets that made him look like an astronaut.

“It was the most challenging suit I’ve ever been on,” the actor acknowledges. “It was crazy dangerous…it’s just super scary. If the air stops, it stops! I really hope that comes over. If it comes over, you have that suspense you need in a movie.”

During his preparation for the film, Hennie dived to 60 metres underwater, “both on heliox and air,” and spent time in decompression chambers.

Meanwhile, Skjoldbjærg and his colleagues studied over underwater films, notably James Cameron’s The Abyss. They also drew on sci-fi movies. Their aim was to “achieve something organic” in the camera and then add digital effects afterwards. They didn’t want simply to rely on CGI.

Pioneer (which has just been pre-sold to Lumiere for Belgium) should be ready for an autumn release.

“It’s a subjectively told story from an industrial pioneer diver’s point of view. It’s the closest thing I’ve done to my debut film Insomnia which was a thriller told from one person’s point of view,” the director reflects.