Jake Gyllenhaal’s ‘Everest’ Director on Pushing Cast to Extremes: ‘I Don’t Really Care for Happy Actors’ (Video)

“I’m not a sadist,” Baltasar Kormakur insists despite testing his actors’ physical endurance in new film

To shoot “Everest,” his fact-based big-screen adventure starring Jake Gyllenhaal and Jason Clarke, director Baltasar Kormakur really pushed the limits.

As he shared with TheWrap’s Steve Pond at the Toronto Film Festival, Kormakur admitted that he took his crew as high as 16,000 feet — a height at which many have gotten “so sick they had to evacuate them with helicopters.”

He also shot the first six weeks of the production in temperatures that were well below zero — in fact, -30 degrees Celsius. “I’m not a sadist,” he said, “but I don’t really care for happy actors.”

Based on a real-life tragedy from 1996, the thriller recounts two different expeditions attempting to reach the summit of the world’s highest mountain.The two groups, led by Scott Fischer (Gyllenhaal) and Rob Hall (Clarke), are challenged beyond their limits when one of the biggest snowstorms in history slams Everest.

The film opens Sept. 18.

Watch the video.