Summer Lake is a large, shallow, alkali lake in Lake County, Oregon, United States located 5 miles (8 km) south of the small, unincorporated community of Summer Lake, Oregon. At high water it is about 15 miles (24 km) long and 5 miles (8 km) wide, and supports a wide variety of birds and other wildlife in its marshes. The lake was named by explorer John C. Frémont on his expedition into Central Oregon in 1843.