Everest director Baltasar Kormákur has told TEN he and his cast and crew did "everything humanly possible" to do justice to the story of the eight mountaineers who died in one day in 1996 in what became the deadliest ever day on on the mountain peak.

In an all-star cast, Jake Gyllenhaal, Josh Brolin, Jason Clarke, Sam Worthington, John Hawkes, Keira Knightley, Robin Wright and Emily Watson play the climbers and their next of kin. 

Jake Gyllenhaal plays Scott Fischer

"One of the main things I wanted it to be [was] authentic on all levels – visually, and also from a character standpoint and from a technical standpoint," said Kormákur. 

When asked about making the sequences as realistic as possible, Kormákur said that while special effects were used, he and his crew refused to depend on them.

"There is green screen and there is CGI, but that is inevitable – that would be like shooting a movie in space. You cannot shoot above a certain elevation because it's just too life-threatening."

Jason Clarke plays Rob Hall

In fact, in their pursuit of authenticity, the Icelandic director and his team actually went to 16,000 feet, where sickness predictably ensued.

"There is a difference between climbing a mountain, resting for two days and climbing again... When you actually have to climb and shoot a whole shooting day as well, then it starts to get really difficult. Shooting on ground zero is difficult for people already – it's hard work – you can imagine doing it up there."   

A camera was also brought to the summit, with Kormákur then travelling to the Dolomites, where filming took place at up to 12,000 feet in temperatures of minus 30 Celsius. 

Everest was made with the co-operation of the survivors and the families of the deceased, and its director was given access to the audio recordings the climbers made on their ascent. 

"We got to know these people and earn their trust," said Kormákur. "As I made it very clear to them, I was not going to sanitise; I was going to humanise. I was not going to make an obituary, but a real story of real people."

Everest is previewing at a number of cinemas this weekend and opens nationwide on Friday September 18. 

Watch Alan Corr's interview with Baltasar Kormákur by clicking the link.