Bohai Bay (simplified Chinese: 渤海湾; traditional Chinese: 渤海灣; pinyin: Bóhǎi Wān) is one of the three bays forming the Bohai Gulf, the innermost gulf of the Yellow Sea, in northeast China. It borders Hebei province and Tianjin Municipality. The three bays are Laizhou Bay to the south, Liaodong Bay to the north, and Bohai Bay to the west.
It is the most southerly sea in the northern hemisphere in which sea ice can form.
The Bohai Bay is the drainage of the Haihe and 15 other rivers. Due to these rivers' muddy runoff, the bay used to be a highly silty water body, but extensive damming of the various river systems has greatly diminish siltage. Nevertheless, the Bohai Bay in effect concentrates the runoff of the whole eastern North China Plain, and the Bay is an intensely polluted body of water.
Fisheries were traditionally some of the richest in China, fed by enormous sediment runoff and extensive shallows to serve as hatcheries. Pollution, eutrophication, habitat destruction caused by land reclamation, and intense overfishing have resulted in a collapse of stocks, and a decline of trawl catch per unit of effort (CPUE) from 138.8 kg/net.hr to 11.2 kg/net.hr from 1959 to 1998.
The Bohai Bay is ringed by several major ports, the Port of Tianjin, the large Port of Tangshan which consists of three ports - Caofedian, Jingtang and Fennan, and the Port of Huanghua, making the Bay into a very crowded waterway. Land reclamation in Tianjin and in Caofeidian have greatly changed the littoral zone, and destroyed much of the area's wetlands. Land reclamation has also affected migratory birds.
As is the case of most of the Bohai Sea, the Bohai Bay is rich in hydrocarbon deposits and has several active offshore oil fields. Jidong Nanpu contains 7,500,000,000 barrels (1.19×109 m3), while the bay as a whole is estimated to contain 146 billion barrels (23.2×109 m3).