Boreas Pass Road climbs about 10 miles from the south end of Main Street to the 11,481-foot summit of Boreas Pass on the Continental Divide. It follows the bed of the Denver, South Park & Pacific narrow gauge — from 1882 to 1937 the highest narrow-gauge railroad in the country — and the steady 3% railroad grade is why the drive feels so gentle. Views sweep the Blue River valley, the Tenmile Range, and Bald Mountain through huge aspen groves; color peaks mid-to-late September.

Railroad relics anchor the route. Bakers Tank, a restored wooden water tower 3.5 miles up, once refilled steam locomotives and still stands beside the road. At the summit, the restored 1882 Section House and Ken's Cabin survive from the railroad settlement of Boreas, once the highest post office in the U.S. The road continues 10.4 miles down to Como in South Park.

Vehicles can drive it roughly late May through October; the unpaved section is graded dirt, passable to most cars in dry conditions. In winter the closed road becomes a favorite ski, snowshoe, and fat-bike route from the winter gate.