If you’ve ever wondered what it’s like for elite climbers operating at extreme altitude, you have to see Meru. You see three of the best mountaineers in the world tackle a climb previously thought impossible. And it’s no ordinary climb– tackling the infamous Shark Fin on Meru required the full gamut of technical skills, from hiking to big wall to ice climbing. All at 21,850 feet.

American climbers Conrad Anker, Jimmy Chin and Renan Ozturk first tried to tackle Meru in 2008. They were beset by bad weather, however, and food shortages and had to make the heartbreaking decision to turn back just 300 feet from the summit. It seemed unlikely the trio would make another attempt. Chin swears on camera as they call off the first attempt that he won’t go back.

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To make matters worse, between 2008 and 2011, Ozturk faced devastating, life-threatening injuries in a horrific skiing accident. Any one of his injuries could have paralyzed or killed him. Yet five months later, Anker had rallied his team into giving the Shark Fin a second try.

What makes Meru such a special documentary is the way the climbers tell their own story in the moment. You watch as they eat couscous for every meal, try to stay warm in the portaledge, and struggle with rains of ice and debris as they follow the climber in the lead position. Through all of it– the climbing, the filming, the psychological grit, altitude is one of their biggest obstacles.

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As Elizabeth Chai Vasarhelyi, Jimmy Chin’s now-wife and co-producer, explained to Mental Floss, “Because it’s high altitude, breathing is an issue. The takes are short because otherwise you’re panting, so they’re holding their breath while shooting a shot.”

That wasn’t the only way that the limitations of the trek shaped the way the documentary was shot. The three-man team had to haul so much gear, including a big wall rig, that they actually cut down on how much food they packed– despite having run out on their first go at the Shark Fin. Add camera equipment to that and limited battery power, and you have a team having to be very judicious about what to shoot and when.

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Despite the careful brevity, Meru doesn’t feel like it gives the viewer short shrift. Instead, you get very intimate with the climbers even as they traverse walls, face medical emergencies, and split a cigarette during their downtime, dangling from a portaledge.

Few of us, however committed to spending time outdoors and testing our bodies’ limits, will ever attempt a feat like Meru. If you’re curious, though, about what man versus mountain looks like up close and personal, this is one of the best films you can watch. Chin’s cinematography gives you a climber-eye-view of what it looks like to dangle off the Shark Fin. More importantly though, it shows just how far we will go to do what has never been done.