Virtsu is a small borough in Lääneranna Parish, Pärnu County, Estonia. It lies on the western coast of continental Estonia, and is a location of the main port for traffic to and from Saaremaa, the largest island of Estonia. The Virtsu ferry goes to Kuivastu, which is located on the island of Muhu, which is in turn connected to Saaremaa by the largest causeway in Estonia, the Väinatamm.