Just north of the resort town of Sapa, Tram Ton Pass (Deo Tram Ton) is Vietnam’s longest and highest mountain pass—and it’s a beauty. Snaking for 75 miles (120 kilometers) through the Hoang Lien Son Mountains, it peaks at roughly 6,200 feet (2,000 meters), where a lookout offers its travelers an aerial taste of the absolute wonders of northwestern Vietnam.