Xiamen is a sub-provincial city in southeastern Fujian whose urban core grew up from the port of Xiamen on southern Xiamen Island, now located within Siming District. It now also includes Gulangyu Island and the rugged coast of the mainland from the northeast bank of the Jiulong River in the west to the islands of Xiang'an in the east. Xiamen Island lies about one degree north of the Tropic of Cancer. It is divided between Huli District in the north and Siming District in the south. Siming also includes Gulangyu. Its mainland territory is divided among Haicang, Jimei, Tong'an, and Xiang'an districts.