Lake Sammamish is a freshwater lake 8 miles (13 km) east of Seattle in King County, Washington, United States. The lake is 7 miles (11 km) long and 1.5 miles (2 km) wide, with a maximum depth of 105 feet (32 m) and a surface area of 8 sq mi (21 km2). 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, named after the native people who once lived along its entire length.

Seattle is a seaport city on the West Coast of the United States. It is the seat of King County, Washington. With a 2022 population of 749,256 it is the most populous city in both the state of Washington and the Pacific Northwest region of North America, and the 18th-most populous city in the United States. The Seattle metropolitan area's population is 4.02 million, making it the 15th-largest in the United States. Its growth rate of 21.1% between 2010 and 2020 made it one of the country's fastest-growing large cities.