Guangdong is located in South China and mainly in the subtropical zone. The province covers an area of about 178 000 sq km (from east to west about 660 km across and 800 km from north down to south), plus about 180 000 sq km marine territory. 60% of the land is mountainous and the rest is composed of tablelands, river valleys, coastal plains and islands. It envelops the Pearl River (Zhujiang) Delta, Chaozhou-Shantou Coastal Plain (mainly the Hanjiang River Delta), mountainous Northern Guangdong, Leizhou Peninsula and the Southwest Coastal Plains. From east to west arranged in an arc are the Yunwu, Qingyun, Jiulian, and Lianhua mountains. Mt.Nanling is the largest in Northern Guangdong, consisting of five ranges: Dayu, Dupang, Mengzhu, Yuecheng and Qitian. So Mt.Nanling is also called Mt.Wuling (five ranges), which is also the watershed of the Pearl River and Yangtze River systems. Shikengkong Peak of Mt.Dadong in Ruyuan Yao Autonomous County in the Northern Guangdong is the highest geographic point of the province, about 1 902m high above sea level.