Pearl, Chin. Zhujiang, river, 110 mi (177 km) long, S Guangdong prov., S China. Formed at Guangzhou by the confluence of the Xi and Bei rivers, it flows E then S past Guangzhou and Huangpu island to form a large estuary between Hong Kong and Macao. The river links Guangzhou to Hong Kong and the South China Sea and is one of China's most important waterways and one of the centers of its world trade. It is vitally important to the special economic zones that lie along its estuary. The estuary, called Boca Tigris, is kept open for ocean vessels by dredging.