Ha Long is a protected bay with smooth waters and light winds. It has a wide range of sea routes and sea ports such as Hong Gai.
Hong Gai, a deep-sea port, provides favorable conditions for the loading and transporting of commodities. Aside from a good climate, the bay has a large tidal area, clean water and rich marine resources in both onshore and offshore fishing grounds.
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 Bay is noted for its many strangely shaped limestone inlets and caves and grottoes.