By Anna Menta

Charlize Theron and Taron Egerton take viewers all over the Australian wilderness in their new thriller, APEX, which began streaming on Netflix today.

Directed by Icelandic filmmaker Baltasar Kormákur, with a screenplay written by Jeremy Robbins, APEX stars Theron as Sasha, an experienced climber grieving the death of her husband (played by Eric Bana). She embarks on a solo hiking-and-kayaking trip in the Australian wilderness, where she meets a friendly local (Egerton) who offers her travel tips. But when she follows the route he suggests, she quickly realizes he isn’t friendly at all. He’s a deranged serial killer, and he wants to hunt the most dangerous game: her.

Theron, a seasoned action star known for doing her own stunts, leapt off cliffs into pools of water and dangled off the side of a mountain, hundreds of meters above the ground. Some of the movie was filmed on sets, but quite a lot of it was filmed in real, remote, and dangerous locations in Australia. “We had to swim to [some of those] locations, with the crew,” Kormákur said in a recent interview with Decider. “We dropped in, in helicopters.”

Read on to learn more about the APEX movie filming locations.

Where was the APEX movie filmed?

For the most part, Netflix’s Apex movie was filmed on location in Australia, as well as some bits in New Zealand. Much of the mountainside scenes were filmed in Australia’s Blue Mountains National Park in New South Wales, in eastern Australia. That included scenes filmed outside the caves in the park’s Grand Canyon, which the crew had to swim to get to.

“The cave—the setting, when they’re getting into the cave—we had to swim to those locations, with the crew,” APEX director Baltasar Kormákur told Decider. “We dropped in, in helicopters. We basically had to scale us down to 40 people, the crew, and swim.”

Other specific locations, according to Women’s Weekly Australia, include Ginninderra Falls, Glenbrook Gorge, Jelly Bean Pool and Royal National Park, as well as some shots filmed at Sydney’s Disney Studios in Moore Park.

While much of the APEX film was shot on location, the director told Decider that “dome of the water work we had to do in a controlled environment. There is an Olympic kayak run in Penrith that we used quite a bit,” Kormákur said, referring to the whitewater stadium built for the 2000 Sydney Olympics.

“But we also shot in crazy rivers, to create the environment and build it,” Kormákur added. “Some of that was done in New Zealand, because we have better access to [rivers] there.”

For some of the climbing sequences, the production built artificial rock walls outside, which, as Kormákur pointed out, was still a risk.

“That was already 20 meters in the air, 60 feet, when people were working on those,” Kormákur said. “Even working on a wall outside, in a more controlled environment, you’re still faced with weather wind, and all those things. It wasn’t a secure environment.”

And some scenes, like the cave interiors, were filmed on sets in a studio.

“But luckily, so far when I’m showing the movie, people cannot tell it apart,” Kormákur said. “I do think it comes from doing the nature first, and putting the emphasis on that, and then implement it with spaces that you have to work in, rather than the opposite.”