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North Cascades National Park

Thornton Lakes Trail

This strenuous day hike or overnight backpack leads to a series of 3 alpine lakes. It is 5.3 miles (one way; 8.5 km) to the first lake. A scramble route to Trapper Peak offers magnificent views.

A 5 mile (8 km) gravel road leaves State Route 20 near milepost 117. The road is narrow and rough. Trailers are not allowed. To park along this road you must have a Northwest Forest Pass, which can be obtained at National Park Service stations in North Cascades or at U.S. Forest Service offices throughout the Northwest.

New Growth
The first 2.3 trail miles (3.7 km) follow an old road grade through a logging area from the 1960s. A natural mix of Douglas-fir, Pacific silver fir, hemlock, cedar, alder, and maples are returning. This lower section can be brushy.

Upper Trail
The trail enters steep forested slopes and after 2.3 miles (3.7 km) breaks out on an open ridge. From here there are views of Mt. Triumph, Teebone Ridge, and the Skagit Valley. The ridge route scrambles steeply to the top of Trapper Peak.

The Lakes
A steep .6 mile (1 km) drop from the saddle ends at Lower Thornton Lake. Use caution when crossing the outlet! These classic cirque lakes were created as glaciers gouged out rock basins, then retreated. Three designated campsites are located near the lake outlet. A primitive path to the upper lakes proceeds from that point.

This is a rich wildlife habitat. Look for deer, bear, marmot, and birds. Observe hawks and eagles during autumn migration.

A permit (no charge) is required for all overnight stays in the backcountry. Camping near Lower Thornton Lake must be at designated sites. Cross-country camping is allowed only at the third lake, Triumph Col, or the ridge to the west of the lakes.

Pets and firearms are prohibited in the National Park; however, hunting is permitted in Ross Lake National Recreation Area. Washington State hunting and fishing regulations apply. Be sure to stop at the Wilderness Information Center in Marblemount (360-873-4500 ext 39). Rangers have maps and current information to assist you in planning a safe, fun trip.




For Additional Information Contact:

North Cascades National Park
2105 State Route 20
Sedro-Woolley, WA 98284-9394
(360) 856-5700


For more information visit the National Park Service website