The key to a good skull-drilling scene, Kirk Watson says, is chopped-up bits of bacon. “You mix it with the fake blood, which is red food coloring, syrup, and flour. That’s for when we had to make brains.”

Watson is an experienced mountaineer who has spent six of the past eight years acting as a field guide for Antarctic scientists, navigating dangerous glaciers and supervising freezing base camps. If he’s looking at brain matter, something has gone horribly wrong. But in 2012, he and colleague Matt Edwards decided to use their free time to shoot a horror film, South of Sanity, while stationed at Rothera Research Station in Antarctica. Though its plot—serial killer picks off hapless researchers at a remote outpost—is mundane, its production was anything but: Sanity is the first horror film ever filmed entirely at the bottom of the world.

After another field guide pulled out of a trip, Watson went to Antarctica on two weeks’ notice, taking his camera equipment and editing software with him. A documentary filmmaker, he had designs on shooting a feature-length movie. Working with Edwards, the two figured the production would be a good way to involve the 21 inhabitants of Rothera—a mix of marine biologists, mechanics, even a chef—in a communal project.

“Come winter, no one is really embarrassed in front of one another anymore,” he says. “I thought I could get some good acting.”

Filming a few days a week over a three-month period, Watson directed 14 amateur performers. While the majority of the movie was shot indoors, he had a few key scenes to shoot in the below-zero temperatures outside of the station. One “dead body” had to be edited out because it kept shivering; another actor grew very agitated because fake blood had leaked into his boot, causing his foot to dampen and freeze up.

“He wanted to go inside,” Watson chuckles, “but I kept doing take after take. He was quite annoyed, but it made his acting a lot better. His foot was supposed to have been chewed up by a snow blower.”

Essentially a one-man crew, Watson had a mechanic build a makeshift crane that could rise 25 feet in the air for more dynamic shots. Surprisingly, the cameras rarely failed despite the climate. “There was sometimes 3mm of ice on them, but they worked brilliantly,” he says. The problem was taking them back inside, where condensation quickly built up: Watson would wrap them in a plastic bin and let the moisture evaporate before resuming filming.

For the “murders,” arterial spray was accomplished using syringes hooked up to tubing that researchers would operate off-screen. Their make-up department consisted of a face paint kit meant for kids. “You have to make do with what you have,” he says. “I found it quite funny when IMDB.com said our budget was a million dollars.”

Watson edited the film as he went along. It was eventually screened for Rothera Research during their annual film festival. (New arrivals found it fun to watch their co-workers get butchered in creative ways.) Sanity eventually had a premiere in Watson’s hometown in Scotland and a DVD and digital release on Amazon and iTunes stateside. Though reviews were mixed, Watson may have made the best possible film he could given the excruciating circumstances of hypothermic conditions and no budget.

“It’s not a particularly good film,” he says. “But it didn’t cost us a penny.”

All images courtesy of Kirk Watson.