The West Estonian archipelago (Estonian: Lääne-Eesti saarestik, also Moonsund archipelago) is a group of Estonian islands located in the Baltic Sea around Väinameri. The total area is about 4,000 km (1,500 sq mi). The archipelago is composed of the islands Saaremaa, Hiiumaa, Muhu, Vormsi and about 900 other smaller islands. The archipelago is separated from the Estonian mainland by the Väinameri Sea.
Saaremaa (/ˈsɑːrəmɑː/; Estonian: [ˈsɑˑreˌmɑː]) is the largest and most populous island in Estonia. Measuring 2,673 km (1,032 sq mi), its population is 31,435 (as of January 2020). The main island of the West Estonian archipelago (Moonsund archipelago), it is located in the Baltic Sea, south of Hiiumaa island and northwest of the Gulf of Riga. The administrative centre of the island, and of the Saare maakond (county), is the town of Kuressaare.
From the 13th century until the first half of the 20th century, the island of Saaremaa was known in most of the world by variants of its other historical name Ösel.
Hiiumaa (US: /ˈhiːʊmɑː, ˈhiːəmɑː/ HEE-uum-ah, -ə-mah, Estonian: [ˈhiːumɑː]) is the second largest island in Estonia and is part of the West Estonian archipelago, in the Baltic Sea. It has an area of 989 km and is 22 km from the Estonian mainland. Its largest town is Kärdla. It is located within Hiiu County.