Bodies of Water Forming China's Borders

China's maritime boundaries are defined by a chain of marginal seas and straits along its ~14,500 km (9,000 mi) coastline. From north to south:

1. Bohai Sea (渤海): Innermost gulf of the Yellow Sea. Enclosed by Liaodong Peninsula (north) and Shandong Peninsula (south). Beijing/Tianjin ports. Semi-enclosed, shallow, heavily industrialized.
2. Yellow Sea (黄海): Between China and the Korean Peninsula. Connected to Bohai Sea (north) and East China Sea (south). Major fisheries, shipping lanes, disputed maritime boundaries.
3. East China Sea (东海): West of Japan's Ryukyu Islands, east of China. Connected to Yellow Sea (north) and South China Sea (south via Taiwan Strait). Contains Diaoyu/Senkaku Islands dispute. Continental shelf <200 m.
4. South China Sea (南海): Largest marginal sea (~3.5M km²). Borders China (north), Vietnam (west), Philippines (east), Malaysia/Brunei/Indonesia (south). China claims ~90% via "nine-dash line"—highly contested. Major shipping route, fisheries, hydrocarbon potential.
5. Taiwan Strait (台湾海峡): 180 km (110 mi) wide, separates Taiwan from mainland China. Connects East and South China Seas. Critical geopolitical flashpoint.

Note: China also borders landlocked/semi-enclosed waters: Caspian Sea (via Central Asia—no direct coastline), Lake Khanka/Xingkai (Russia border), and numerous border rivers (Amur, Ussuri, Mekong/Lancang, etc.).