Loon Lake is a 294 acre lake in Douglas County in the Oregon Coast Range of the United States, 15 mi east-southeast of Reedsport, Oregon, at an elevation of 392 ft. The lake is about 2 mi long with a maximum width of about 0.4 mi, and is over 100 ft deep in some places. The lake is "a classic example of a landslide lake", dammed by a slide of sandstone blocks which fell into the Lake Creek valley about 1,400 years ago. The lake was discovered in 1852 and named for the loons found on its waters.