Summit County, a mere hour's drive from the Denver Metro Area on a straight shot up I–70, is Denver's playground. The wide-open mountain park ringed by 13,000- to 14,000-foot peaks greets westbound travelers minutes after they pop out the west portal of the Eisenhower Tunnel. The sharp-toothed Gore Range rises to the northwest and the Tenmile Range gathers up behind Breckenridge. Resting in the center of this bowl are the sapphire waters of Dillon Reservoir, an artificial lake fed by Blue River.
In winter, Summit County is packed with tourists and Front Range day-trippers skiing the steeps at Breckenridge, Keystone, Arapahoe Basin, and Copper Mountain. The high density of first-rate ski resorts generally keeps lift lines low, particularly on weekdays. In summer, the steady westbound traffic is mostly SUVs stacked high with kayaks and mountain bikes.
Summit County, as its name implies, is relatively high. The town of Breckenridge sits at 9,603 feet (Aspen by comparison is at 7,908 feet), and the resort's highest ski lift tops out just shy of 13,000 feet. Visitors from sea level should take their time getting acclimated. Even Denverites find themselves breathless in the thin air. Drink lots of water and rest your first few days. There will be plenty of time to play.