Washington State Ferries (WSF) is a government agency that operates automobile and passenger ferry service in the U.S. state of Washington as part of the Washington State Department of Transportation. It runs ten routes serving 20 terminals located around Puget Sound and in the San Juan Islands, designated as part of the state highway system. The agency maintains the largest fleet of ferries in the United States at 21 vessels. In 2021, the system had a ridership of about 46,900 per weekday as of the second quarter of 2022. As of 2016, it was the largest ferry operator in the United States and the second-largest vehicular ferry system in the world.