It adjoins Wuling Mountains to the north and the South China Sea to the south, with a landscape sloping from north to south. It's mountainous in north, and in the south there are coastal plains, hills and tablelands. The deltas of the Pearl River and Han River are its chief plains. The West River, the North River and the East River, known as "the Peal River System", as well as Han River are Guangdong's main waterways. Its coastal line is long and zigzag with numerous offshore islands.