The Bohai Sea is a gulf/inland sea approximately 77,000 km2 (30,000 sq mi) in area on the east coast of Mainland China. It is the northwestern and innermost extension of the Yellow Sea, to which it connects to the east via the Bohai Strait. It has a mean depth of approximately 18 meters (59 ft), with a maximum depth of about 80 meters (260 ft) located in the northern part of the Bohai Strait.

The Yellow Sea, also known as North Sea, is a marginal sea of the Western Pacific Ocean located between mainland China and the Korean Peninsula, and can be considered the northwestern part of the East China Sea. It is one of four seas named after common colour terms, and its name is descriptive of the golden-yellow color of the silt-ridden water discharged from major rivers.