Lake Washington, Freshwater lake in King County, US

Lake Washington is a freshwater lake in King County between Seattle, Bellevue, and Renton in Washington state. The body of water stretches across a large area with gentle shores, wooded slopes, and two floating bridges connecting its eastern and western sides.

Lake Washington drained south through the Black River into the Duwamish Valley until the Lake Washington Ship Canal opened in 1916. The canal became the lake's only outlet, and the water level fell nearly nine feet (2.7 m), drying up the Black River. The Cedar River was diverted into the lake to become its main source, and the Montlake Cut links it to Lake Union and Puget Sound.

The lake's name was proposed in 1854 by Thomas Mercer to honor George Washington, a year after Washington Territory was created. The Duwamish and other Indigenous peoples had long called it x̌ačuʔ, meaning "lake" in Lushootseed; Chinook Jargon speakers used Hyas Chuck, "great water." Today the lake supports boating and sport fishing for sockeye, coho and Chinook salmon, rainbow trout and bass.

Several public parks along the shore offer access to the water with parking and restrooms. Swimmers should be cautious during windy weather when waves can form quickly.

On clear days you can see Mount Rainier rising beyond the Seattle skyline from the eastern shore. Divers can explore submerged trees and historic boat wrecks resting on the bottom.