Geography of Taiwan its narrowest. Part of the continental shelf, the Strait is no more than deep, and has become a land bridge during glacial periods. To the south, the island of Taiwan is separated from the Philippine island of Luzon by the -wide Luzon Strait. The South China Sea lies to the southwest, the East China Sea to the north, and the Philippine Sea to the east. Smaller islands of the archipelago include the Penghu islands in the Taiwan Strait west of the main island, with an area of , the tiny islet of Xiaoliuqiu off the southwest coast, and Orchid Island
Mainland China in English, is commonly applied by SAR governments to represent non-SAR areas of PRC, including Hainan province and coastal regions of mainland China, such as "Constitutional and Mainland Affairs" () and Immigration Departments. In the Mainland and Hong Kong Closer Economic Partnership Arrangement (as well as the Mainland and Macau Closer Economic Partnership Arrangement) the CPG also uses the Chinese characters "inner land", with the note that they refer to the "customs territory of China". In the United States' Taiwan Relations Act, the ROC-controlled islands of Quemoy and Matsu were excluded from the definition of "Taiwan". The House Foreign Affairs