Territorial sea in the context of "Internal waters"

The Bohai Sea (Chinese: 渤海; pinyin: Bó Hǎi; lit. 'Bo Sea') is a gulf/inland sea approximately 77,000 km (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 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 Bohai Sea is enclosed by three provinces and one direct-administered municipality from three different regions of China—Liaoning Province (of Northeast China), Hebei Province and Tianjin Municipality (of North China), and Shandong Province (of East China). It is the center of the Bohai Economic Rim, and its proximity to the Chinese capital of Beijing and the municipality of Tianjin makes it one of the busiest seaways in the world. The entrance to the Bohai Sea is considered a part of the territorial sea of the People's Republic of China due to the presence of the Miaodao islands. China declared the Bohai sea to be part of its inland waters in 1958.

A baseline, as defined by the United Nations Convention on the Law of the Sea, is the line along the coast from which the outer limits of a state's territorial sea and certain other maritime zones of jurisdiction are measured, such as a state's exclusive economic zone.

Innocent passage is a concept in the law of the sea that allows for a vessel to pass through the territorial sea (and certain grandfathered internal waters) of another state, subject to certain restrictions. The United Nations Convention on the Law of the Sea Article 19 defines innocent passage as:

Underwater vehicles like submarines are required by the treaty to surface and show their flags during innocent passage.