The sky is gunmetal gray, a shade somewhere between inviting and malicious. We’re 40 miles due east of Tromsø, Norway, a city that sits on the Norwegian Sea more than 180 miles north of the Arctic Circle. Yesterday, kiteboarders were ripping across the frigid late-April water propelled by gusty winds, a testament to the commonly held belief that of the three Scandinavian bloodlines—Norwegian, Danish, and Swedish—Norwegians are the most hardcore. The proponents of that stereotype, however, have yet to meet Kenth Fjellborg, Arctic Swede.

“Get dressed! Put your boots on!” Fjellborg shouts to jolt us out of the heated van. “When we get going, we’re not going to stop! The sun is hiding in the sky, but we’re going to go right into the white! Men, you do the number one outside. The outhouse is not for gentlemen. But I hate it when pee is spread over the snow.”

It’s the first morning of our journey, and the marching—or, rather, mushing—orders have begun. Six of us, all neophytes, will be guided by Fjellborg on one of his most rigorous Arctic dogsledding adventures. We’re lined up like a United Nations train: Fjellborg is in front; the three American, one British, and two Swedish sledding rookies are in the middle; and 26-year-old Norwegian-­Scottish guide Amanda Calder, who wears two knives at all times—one for dogs and one for ­humans—brings up the rear.

We’ll each lead a team of five or six dogs on a five-day, 160-mile journey from the old Rognli homestead, which sits in the Signal Valley, on a historic backcountry “highway” between Norway and Sweden. We’ll climb 2,400 feet into the Arctic tundra, then travel southeast along frozen waterways that will lead us to Fjellborg’s home in the Swedish village of Poikkijärvi. Poikkijärvi is on the banks of the Torne River, directly across the water from Jukkasjärvi, the village Fjellborg’s ancestors first inhabited in 1690. Nine ­generations of Fjellborgs have lived within a 25-mile radius of Jukkasjärvi ever since.

But first, a dose of äkta svensk ­gästfrihet—genuine Swedish hospitality. Cooking over an open fire, Fjellborg and his pit crew of two, who helped transport our 46 dogs and will leave us here, have set out a small smorgasbord of reindeer stew, lingonberry jam, and mashed potatoes, along with that staple of the Swedish backcountry diet, ­polar bread—a whole wheat pita topped with ­butter and cheese.

The hearty brunch, inspired by the Sami, who have herded reindeer in the northern latitudes for 8,000 years, will fuel us until we reach Pältsa, the Swedish Tourist ­Association’s northernmost mountain hut, which will be our home our first night and sits across the border in Sweden, about 20 miles from here, at 68.8 degrees north latitude. The hut was used during World War II as a base for Norwe­gian resistance fighters. Farther along the trail, we’ll stay at a Sami-run fishing camp, then at the residence of an old Swedish family who’ve lived here ­almost as long as the Fjellborg clan, and, finally, at Sevuvuoma, an ancestral Fjellborg homestead, which Fjellborg bought from a distant cousin and has recently renovated. From there we’ll mush roughly 20 miles to his house in Poikkijärvi.

“Do you know the Sami word for ‘vegetarian’?” Fjellborg asks. “Poor hunter!”

Then he gets down to business.