Muhu (in German Moon or Mohn; in Estonian also called Muhumaa), is an island in the Baltic Sea. With an area of 198 km² it is the third largest island belonging to Estonia, after Saaremaa and Hiiumaa. The island is divided from mainland Estonia by the Suur Väin Straits (Moonsund) and from Saaremaa by Väike Väin Straits. It is linked by ferry to Virtsu on the mainland, and to Saaremaa by a causeway, the Väinatamm. In winter an ice road connects the island to the mainland.