The view below is pretty spectacular. From a window on a 20-seat airplane, which departed from Punta Arenas, you have a view of the Strait of Magellan, the islands that make up Tierra del Fuego and the southernmost tip of South America, and vast glaciers. Argentina is to the east. Cape Horn is to the south. Then it’s just frigid water until you reach Antarctica.

Don’t worry, you aren’t traveling that far—this time. You’ve come to Patagonia to go hiking in the Dientes de Navarino on Isla Navarino (Navarino Island). The mountain range, whose jagged peaks look like sharp teeth, are just starting to come into view. There are no trees on these mountains, just steep rock faces, snow caps, and, by the sound of it, lots of wind. It’s also home to the Dientes Circuit.

The Dientes Circuit is a 19-mile, five-to-seven day hike through these otherworldly mountains. It starts and ends in Puerto Williams, the small capital of the Chilean Antarctic Province. For years, it was mostly historians, archaeologists actually, who traveled this far south. They came to study the archaeology-rich island, where the Yaghan people, a nomadic tribe, survived under extremely harsh conditions. Recently, adventure sports enthusiasts—sea kayakers, rock climbers, and hikers, like yourself—have caught on.

Begin by checking in with the authorities in Puerto Williams—someone should know where you’re heading—and following the guanaco (a llama-like animal) path to Cerro Bandera and the beginning of the trail markers. Keep a close eye out for them; the cairns (rock piles) are painted red, though they’re few and far between. Plus you have views of the Beagle Channel when you turn around.

After climbing Cerro Bandera, you pass glacial lakes and cross icy streams. You watch for beavers and follow a condor. You search for a safe place to tie down your tent and miss the refugios that dot the rest of Patagonia. You lose the trail and your footing on slippery rocks more times than you can count. Eventually, you descend into a densely forested valley. Make no mistake, the Dientes Circuit is punishing. But it’s a hike you’ll remember for the rest of your life.