Xiamen Island is the fourth largest island in Fujian province. It became a peninsula after the completion of the seawall in 1955. Xiamen waters include Xiamen Port, Outer Harbor Area, Maluan Bay, Tongan Bay, Jiulong River's estuary area and the waterway on the east side. Outside the Xiamen Port, Big Kinmen, Little Kinmen, Dadan, Erdan and other island are arranged in a horizontal line. Inside, it has Xiamen Island, Gulangyu Island and other island barriers, making it a good natural port protected from storms.