The East China Sea is a marginal sea of the Western Pacific Ocean, located directly offshore from East China. China names the body of water along its eastern coast as "East Sea" (Dōng Hǎi, simplified Chinese: 东海; traditional Chinese: 東海) due to direction, the name of "East China Sea" is otherwise designated as a formal name by International Hydrographic Organization (IHO) and used internationally.
It covers an area of roughly 1,249,000 square kilometers (482,000 sq mi). The sea's northern extension between Korean Peninsula and mainland China is the Yellow Sea, separated by an imaginary line between the southwestern tip of South Korea's Jeju Island and the eastern tip of Qidong at the Yangtze River estuary.