Lake Sammamish State Park is a park at the south end of Lake Sammamish, in King County, Washington, United States. The park, which is administered by the Washington State Park System, covers an area of 512 acres and has 6,858 feet of waterfront; Issaquah Creek meets with Lake Sammamish within the park. It is a popular location for boating and watersport activities, such as waterskiing. The State Park is accessible from Interstate 90 at exit 15 and the north end of State Route 900.