Lake Sammamish is a freshwater lake  east of Seattle in King County, Washington, United States. The lake is long and wide, with a maximum depth of and a surface area of . It lies east of Lake Washington and west of the Sammamish Plateau, and stretches from Issaquah in the south to Redmond in the north. At Issaquah it is fed by Issaquah Creek, and at Redmond it drains to Lake Washington via the Sammamish River.