port city, northeastern Vietnam. Hong Gai lies along Ha Long Bay of the Gulf of Tonkin, about 25 miles (40 km) northeast of Haiphong. It is an export centre for coal mined at nearby Quang Yen, the site of anthracite deposits that are the largest in Southeast Asia. Other economic activities in the area are rice farming and fishing. Ha Long (Ha Long Bay) Bay is noted for its many strangely shaped limestone inlets and caves and grottoes. Pop. (1989) 123,102; (1992 est.) 127,484.