Until the early 20th century, Bo Hai was often called the Gulf of Chihli or the Gulf of Pechihli or Pechili. Zhili and Beizhili were historic provinces in the area surrounding Beijing.
The opening of the Bohai Gulf is bounded by Changshan Archipelago between Dalian's Lüshunkou District on the southern tip of Liaodong Peninsula, and the Cape of Penglai on the northernmost protrusion of Shandong Peninsula. Due to its proximity to the capital city Beijing and the population of its surrounding provinces exceeding 210 million, the exit of the Bohai Gulf to the Yellow Sea, the Bohai Strait, has become one of busiest sea routes in recent times. Due to the Changshan Island Chain traversing the southern half of the strait, the Bohai Strait is subdivided into several channels:
Laotieshan Channel, also known as the Lau-ti-shan Channel, is the widest and deepest
Daqin Channel
Xiaoqin Channel
North Tuoji Channel
South Tuoji Channel
Changshan Channel, is the most direct route to Tianjin
Dengzhou Channel, also known as the Miaodao Channel or Miaodao Strait, is the nearest to the shore but also the shallowest
Major ports
There are five major ports along the Bohai Sea rim, with throughputs over 100 million tons, though the port of Tangshan is further subdivided into Jingtang and Caofeidian:
Caofeidian and Jingtang are usually treated as one port for statistical purposes. The ports of Dalian and Yantai are also traditionally considered part of the Bohai rim, even though strictly speaking they lie outside the limits of the sea. The Port of Longkou reached 70 million tons of cargo in 2013, and is expected to reach the 100 million ton landmark in the near future.
The Bohai Bay contains significant oil and gas reserves, which provide much of China's offshore production. The main field in the region, named Shengli, has been exploited since the 1960s. It still produces about half a million barrels a day, but is declining. Production is dominated by Chinese majors but foreign companies are also present, like ConocoPhilips, Roc Oil, and others. The Gudao Field, located in the Zhanhua sedimentary basin, was discovered in 1968, based on gravity, magnetic and seismic surveys conducted between 1963–1964. The reservoir includes the Guantao and Minghuazhen geologic formations within the dome-like anticline. The Suizhong 36-1 Oil Field was discovered in 1987, and produces from Oligocene fluvial-deltaic and lacustrine sandstones. Oil spills have been reported frequently in this region: three spills occurred in a two-month timeframe in 2011.
Tunnel crossing
In February 2011, the PRC announced that it would build a road and rail tunnel across the Bohai Strait to connect the Liaodong and Shandong peninsulas. When completed, the tunnel would be long. This plan seems to have been superseded as of July 2013, with a modified plan involving a tunnel between Dalian, Liaoning and Yantai, Shandong. The overall concept had its origins in a 1994 plan, which had been intended for completion by 2010 at a cost of $10 billion.