Castle Lake, CA

Castle Lake is a glacial lake (cirque lake or tarn) located in northern California along the eastern edge of the Klamath Mountains, in Siskiyou County, near the city of Mount Shasta. The outlet of the lake drains into Castle Lake Creek, and then into Lake Siskiyou; the lake is part of the headwaters of the Sacramento River. Nearly all of the lake's 47 acres (19 ha) are within the Shasta-Trinity National Forest.

Trails lead from Castle Lake into the adjacent Castle Crags Wilderness Area, and on to Castle Crags State Park, including trails to Little Castle Lake and Heart Lake. Fishing, camping, and hiking are also available at or near the lake. The lake and the surrounding area contain a wide variety of animals and plants including trout, bears, deer, otters, frogs, and osprey.  The lake  is  fed  primarily by snow melt and spring flow.  The bottom is almost entirely flocculent mud, except where emerging springs expose gravel.

The lake is usually reached by driving along an approximately 7 mi (11 km) road from Lake Siskiyou. About one-quarter mile (400 m) north of Castle Lake is a campground. At the lake itself, fishing and picnicking, as well as viewing the local plant life, wildlife and scenery, are common activities. The lake waters can be cool, so swimming is generally limited to summer months. Kayaking, rowboating and rafting are available on the lake. In the winter, in addition to cross-country skiing and snowshoeing along the trails in the area, the lake will ice over and ice fishing is a common activity.