While sea level denizens are out grilling in shorts and sandals, the Swiss are still enjoying the last weeks of a long ski season. And every two years, in the beginning of May, an historic ski mountaineering race takes place: the Patrouille des Glaciers, “the Glacier Patrol”. Originally conceived in the 1940s as a way to train the military to defend its Alpine ramparts from neighboring Nazis, the race was opened up to the public in 1984, sans guns. To Americans the event might seem niche, but not so for the Swiss; the race, a national treasure of sorts, attracts close to 5,000 participants of all ages and ability levels and tens of thousands of rowdy Swiss spectators who line the course.

MORE SPRING SKIING: Power of 4 Ski Mountaineering Race | Breckenridge Peak 6

But the Patrouille is no 5K fun run. Teams of three race from the town of Zermatt in the shadow of the Matterhorn over mountain passes, traversing glaciers and skiing down icy chutes to finish 35 miles later at the picturesque ski station town of Verbier. Over the course of those kilometers the racers gain a ridiculous 12,000 feet of elevation, crossing high passes including the 14,000-foot Dent Blanche. The fastest teams finish in around eight hours. Most come in between the 10 and 14 hour marks. Slow teams are pulled from the course if they don’t make time cutoffs.

The Patrouille is still conducted by the Swiss military, who lay the course, set up checkpoints and oversee safety — which is a primary concern. In 2012, the race was cancelled after numerous postponements due to bad weather. This year, it was postponed due to heavy snow, and two skiers disappeared during a training outing and have yet to be found.

JEANRICHARD’S SPECIAL EDITION RACE WATCH

JeanRichard-Sidebar-Gear-Patrol

Swiss watch company JeanRichard was official timekeeper for this year’s race, now in its 30th year since it was opened to the public in 1984. JeanRichard, based in La Chaux-de-Fonds, also released a limited edition Patrouille des Glaciers version of its Terrascope watch. In addition to some commemorative text on the case back, it features a grey rubber strap and a dial engraved with a textured topographical map of the race course. The Patrouille may seem like an odd, niche event for a watch company to choose to partner with, but the race is hugely popular in Switzerland, making the news alongside politics and Roger Federer. JeanRichard’s Managing Director, Bruno Grande, is an avid skier who had plans to compete this year until he was sidelined by illness during training. He promises to be on the start line in 2016.

This year’s race finally started last week, on a rainy cool night in Zermatt. Racers set off in waves right down the town’s main street and headed into the mountains, running until they hit snow before strapping on their randonee skis and skins. Though they must travel light, ski mountaineering requires being prepared for anything, so packs are stuffed with extra layers, an ice axe, crampons and bivouac gear.

We were in Zermatt for the start of the race and then hopped aboard a helicopter to beat racers to the finish at Verbier. The chopper ride was a thrilling VIP way to follow the race, complete with dramatic liftoffs, a circuit of the Matterhorn and vertiginous views. Check out our photos above.