Conrad Anker, Jimmy Chin, and Renan Ozturk made history in 2011 by becoming the first people ever to reach the summit of the central peak of Mount Meru, a nearly 22,000-foot-tall mountain in the Gharwal Himalayas. Today, MERU—a documentary about the trio’s experience, filmed by the men as they climbed—is hitting theaters. We sat down with co-directors Chin and E. Chai Vasarhelyi to talk about what makes the mountain special, why it’s so tough to climb, and how the men went from filming their journey for posterity to making a feature length doc.

1. IT’S THE ANTI-EVEREST.

Outside of serious climbers, few know about Mount Meru, which is the opposite of the most famous Himalayan mountain in many ways. “As a professional climber, everybody’s like, ‘Have you ever climbed Everest?’” says Chin, who has climbed that mountain twice and once skied down from the summit. “It’s what people are familiar with, and it’s created this stereotype of mountain climbing: People with big down suits walking up a big slope.” 

But the Shark's Fin route up the northwest side of Meru’s central peak is a much tougher, and more technical, climb: Those looking to make the 20,700-foot summit need to carry 200 pounds of gear—there are no Sherpas to haul heavy loads at Meru, as there are at Everest—and be very, very experienced in all kinds of climbing, from mixed ice to big wall. There’s 4,000 feet of technical climbing before hitting the route’s most daunting feature, a 1,500-foot stretch of nearly featureless granite. 

“You can show up at Everest having never really climbed before, because it’s like hiking, basically,” Chin says. “You can’t show up on Meru and start up the thing unless you have years and years of experience. Climbing and spending time on the mountains is really the only way you can train.”

2. MANY PEOPLE HAVE TRIED TO CLIMB IT—AND FAILED.

Climbers had been trying to conquer the Shark’s Fin route for 30 years before Anker, Chin, and Ozturk made it in October 2011. According to Chin, before the trio’s 2008 ascent (when bad weather delayed their progress up the mountain and, facing food shortages, they were forced to turn back just 300 feet from the peak), “the highest attempt had basically only gotten halfway.” One climber even broke both legs in the attempt. “The top climbers in the world had attempted this climb and couldn’t do it,” Vasarhelyi says. “That history is what makes Meru special.

“If there’s a known route that’s kind of stunning and beautiful and has that aesthetic, just having that many failures on it, in itself, draws more climbers towards it,” Chin says. “Having it go 30 years with that many [unsuccessful] attempts is a long time.”

3. THERE AREN’T MANY OTHER ROUTES LIKE THIS ONE.

Though there are a number of other challenging routes up mountains, including on Meru's other peaks, “I don’t know of many [routes] specifically like the Shark’s Fin because the upper head wall was overhanging, and that just doesn’t happen geologically that much," Chin says. 

4. THREE CLIMBERS IS THE MAGIC NUMBER.

And there are two main reasons why: “One, if somebody gets injured, you have two people to help evacuate him,” Chin says. More than three people, and you’d need more equipment, including two portaledges (hanging tents that are anchored into the rock thousands of feet above the ground) and the weight of all the gear would become too much. But with a three-person team, “you can get everybody in one portaledge, and then you can always have one team climbing, like one person leading, one person belaying, and then the third can either be resting, melting snow, organizing gear,” Chin says. “There’s a certain efficiency to it.”

5. THE FALL IS THE BEST TIME TO CLIMB.

The Himalayas have two main climbing seasons, in the spring and in the fall. “Geographically, one season favors one part of the Himalayas and one season favors another part,” Chin says. “For the Garhwal, the fall is great because supposedly the weather is a little bit more stable.” But there’s a downside to a fall climb: “It does usually mean it’s a lot colder, and the days are getting shorter.”

6. GETTING DOWN TOOK THREE DAYS.

The trio’s 2011 ascent took 11 days, and they made it back down in just three. “It’s a lot easier, but it’s way more dangerous,” Chin says. “Statistically, most accidents happen during the descent.”

7. BRINGING ALONG EQUIPMENT TO FILM MEANT SACRIFICING FOOD.

Chin and Ozturk are both filmmakers, and shot their journeys up Meru in both 2008 and 2011. But bringing along the cameras and batteries to shoot meant making sacrifices. When you’re climbing and dragging gear with you, “weight is a really big deal,” Vasarheyli says. “They cut the labels out of their jackets and the handles off their toothbrushes. The 15 pounds of camera gear is equivalent to two days of food, which they certainly could have used on the first climb. There’s really only two hours of direct sunlight a day, so it made no sense to bring a solar charger, so instead they weighed the charger and said ‘OK, this weight would be equivalent to this many batteries, so we can bring this many extra batteries.’ Those kinds of calculations are stunning to think about.”

There were other challenges presented by filming while climbing, too: No shot could hold up the climb, and whoever was filming had to hold his breath so as to not disrupt the shot. “Because it’s high altitude, breathing is an issue,” Vasarhelyi explains. “The takes are short because otherwise you’re panting, so they’re holding their breath while shooting a shot.” The various restrictions on filming meant there was not a lot of footage when they came off the mountain.

8. THE MEN WERE ORIGINALLY DOCUMENTING FOR POSTERITY, NOT A FILM.

Chin says he never even considered turning the film into a feature-length documentary until after the 2011 climb. “It just seemed very daunting, but it struck me that there was enough going on with all the characters, and there was also this motivation to share some aspects of climbing that have always been really important to me, which I didn’t feel like people understood or got—the friendship, and the mentorship, and kind of the loyalty,” he says. 

He began assembling rough cuts, and showed them to Vasarhelyi in 2012. “I had never seen footage like this, and it was unique to the situation and the particular skill set of the climbers and the fact that there are three of them and they’re filming each other,” she says. “We had this wonderful footage, but the question, I think, when you make a feature-length doc is, are there ways that people who aren’t familiar with climbing can identify with the story?”

So she stepped behind the camera to interview the climbers and their families to flesh the film out. “I’m not a climber, so I was very interested in the human story,” she says. “That’s what happens in feature docs. The more time you spend, the more nuance emerges, the more a story evolves—but it’s different than fiction where you can reshoot something. There’s no reshooting on Meru.” 

9. NO ONE HAS MADE IT TO THE TOP OF THE SHARK’S FIN ROUTE SINCE.

Chin credits the trio’s success where so many others had failed to a few things: better weather; what they learned from their first climb; and, mostly, Anker, for whom the third attempt to climb the mountain was the charm (before the 2008 attempt, he tried his luck in 2003). “Conrad had 30 years of experience climbing,” Chin says. “That type of climbing—alpine, big wall climbing—is his kind of specialty, and he’s also this very innovative character. He’s always open to trying new things. He’s a strategist, and he’s very detail oriented. When it comes to our climbing systems, everything has to be the most efficient. His expectations are very high. He deserves a lot of the credit.”

And though no one has completed the route since he, Anker, and Ozturk did, Chin has a prediction: “There’s a very, very, very small percentage of really hardcore climbers who will watch the movie and be like, ‘I want to go there,’” he says. “But 99.9999 percent of people would never want to go there after they watch [the doc].”