 The east coast of Shi Wei Mountain () on Dongyin is the easternmost of the Matsu Islands (26。 23’ 08’’N, 120。 30’ 08’’ E), while the north coast of Beigu Reef () on Xiyin (Siyin) is the northernmost of the Matsu Islands.Dongyin itself is the northernmost point of the territory of the Republic of China (Taiwan).The islands are the key transportation hub between Mawei and Shanghai, and are of strategic importance in the Taiwan Strait area.