Hike the Arapaho Glacier Trail
At the Fourth of July Mine, you can gain access to the Arapaho Glacier Trail. The mine was built during the gold and silver rush in the 1870's—a horse-drawn whim used for raising ore lies near the shafthouse. From the mine, the trail switchbacks up Caribou Ridge for 1.5 miles until it reaches Arapaho Saddle. Although no technical climbing equipment is necessary, the narrow ridge is steep and requires some scrambling. At the highest point on the trail, hikers are rewarded with spectacular overlooks of the Arapaho Glacier, the North Arapaho (13,502 feet) and South Arapaho (13,397 feet) Peaks. Also visible are Silver Lake, Island Lake, Goose Lake, and Triple Lakes—all of which serve as watershed for the City of Boulder.

Ski North America's Highest Ski Area
Arapahoe Basin, or A-Basin as the local snowboard bums call it, boasts a summit elevation of 13,050 feet, which makes it the highest skiable terrain in North America. High-altitude skiing and snowboarding have their perks: A-Basin gets over 360 inches and 300 days of sunshine. These ideal conditions allow the slopes to remain open from November to June—one of the longest ski seasons on the continent.

Camp along the "Great Lakes of Colorado"
In the upper reaches of the Colorado River Valley, the Arapaho National Recreation Area is sometimes referred to as the "Great Lakes of Colorado." The area encompasses five major lakes and reservoirs including Lake Granby, Shadow Mountain Lake, Monarch Lake, Willow Creek Reservoir, and Meadow Creek Reservoir. Just outside the area sits Grand Lake—the largest natural lake in Colorado. For lakeside camping, consider Stillwater Campground—at an elevation of 8,300 feet, Stillwater sits on the western shoreline of Lake Granby and offers 127 sites. It is the only Forest Service campground in the area that offers amenities like showers and restrooms. The campground has a tendency to fill up quickly in the summer.

Trout Fish at Devil's Thumb
Devil's Thumb, at 11,260 feet, offers high-altitude trout fishing for cutthroat. The 11.5-acre lake is 37 feet deep and offers fishermen the necessary solitude to achieve a state of mountain Zen. Not high enough? Try the 100-foot deep Dorothy Lake situated at an elevation of 12,061 feet. Rainbow, brook, and brown trout, along with kokanee salmon, occupy the cold waters of dozens of mountain lakes throughout the Boulder Ranger District.