East China Sea
Marginal sea of the Western Pacific, bordered by East Asian nations.
Wikipedia / Wikimedia Commons
The East China Sea is a marginal sea of the western Pacific, lying off the coast of East China. While China refers to it as the "East Sea" (Dōng Hǎi) based on cardinal direction, the International Hydrographic Organization (IHO) has formally designated it as the "East China Sea," a name used internationally. It spans roughly 1,249,000 square kilometers (482,000 square miles). The sea is largely shallow, with nearly three-quarters of its area less than 200 meters (660 feet) deep. Its average depth is about 350 meters (1,150 feet), and its deepest point, in the Okinawa Trough, reaches 2,716 meters (8,911 feet). The Korean Peninsula, China, Japan, and Taiwan all border or lie within this sea.
The sea's northern boundary connects to the Yellow Sea, separated by an imaginary line running from the southwestern tip of South Korea’s Jeju Island to the eastern tip of Qidong at the Yangtze River estuary. To the east and southeast, it is bounded by the middle section of the first island chain off the Eurasian mainland, including Japan’s Kyushu and the Ryukyu Islands. To the south lies Taiwan. The East China Sea connects to the Sea of Japan via the Korea Strait, to the South China Sea through the Taiwan Strait, and to the Philippine Sea through gaps between the Ryukyu Islands, such as the Tokara and Miyako straits.
The Yangtze River is the largest river flowing into the sea. In the northern part, a cluster of submerged reefs includes Socotra Rock (also called Suyan Rock or Ieodo), which is subject to an exclusive economic zone (EEZ) dispute between China and South Korea, as well as Hupijiao Rock and Yajiao Rock.
Historically, American whaleships hunted right whales in these waters from 1849 to 1892. Naming conventions vary: in Chinese, it is the East Sea, one of the Four Seas of Chinese literature. In Japanese, it was called 東支那海 (Higashi Shina Kai) until World War II, but by 2004 official documents had switched to 東シナ海 (pronounced the same). In Indonesia, the name Laut Cina Timur was used until 2014, when the government changed it to Laut Tiongkok Timur, though many media outlets still use the older term.
EEZ disputes exist among China, Japan, Taiwan, and South Korea over the sea’s maritime boundaries. China and Japan both claim 200-nautical-mile EEZ rights, but the sea is only 360 nautical miles wide. China argues for a natural prolongation of its continental shelf extending to the Okinawa Trough, citing the United Nations Convention on the Law of the Sea (UNCLOS), and submitted a claim to the UN in 2012. Japan, however, asserts that about 40,000 square kilometers of this area falls within 200 nautical miles of its coast and advocates for a median line division.
- Area
- Roughly 1,249,000 square kilometers
- Average Depth
- 350 meters
- Maximum Depth
- 2,716 meters (Okinawa Trough)
- Bordering Countries
- South Korea, Japan, Taiwan, China
- Major Inflow River
- Yangtze River
- International Name Designator
- International Hydrographic Organization (IHO)
Verified Timeline
Lore & Background
The East China Sea is called the East Sea in Chinese (东海; 東海; Dōng Hǎi), and is one of the Four Seas of Chinese literature. Until World War II, the sea was referred to as 東支那海 (Higashi Shina Kai; "East Shina Sea") in Japanese. In 2004, official documents of the Japanese Foreign Ministry and other departments switched to the name 東シナ海 (pronounced the same), which has become the standard usage in Japan. Common usage in Indonesia referred to the sea as Laut Cina Timur until 2014, when Indonesia switched usage from the word Cina to Tiongkok instead; since then, the name Laut Tiongkok Timur become standard usage in Indonesia. American whaleships cruised for right whales in the sea between 1849 and 1892. There is a cluster of submerged reefs in the northern East China Sea, including Socotra Rock, also called Suyan Rock or Ieodo, a subject of an EEZ dispute between the People's Republic of China and South Korea.
Reader's Guide
The East China Sea is bounded in the east and southeast by the middle portion of the first island chain off the eastern Eurasian continental mainland, including the Japanese island of Kyushu and the Ryukyu Islands, and in the south by the island of Taiwan. It connects with the Sea of Japan in the northeast through the Korea Strait, the South China Sea in the southwest via the Taiwan Strait, and the Philippine Sea in the southeast via gaps between the various Ryukyu Islands (e.g. Tokara Strait and Miyako Strait). The Yangtze River (Chang Jiang) is the largest river flowing into the East China Sea. There are disputes between China (PRC), Japan, Taiwan, and South Korea over the extent of their respective exclusive economic zones (EEZ). In 1995, the People's Republic of China (PRC) discovered an undersea natural gas field in the East China Sea, namely the Chunxiao gas field, which lies within the Chinese EEZ while Japan believes it is connected to other possible reserves beyond the median line. In June 2008, both sides agreed to jointly develop the Chunxiao gas fields, but they have never been able to agree on how to execute the plan. Taiwan, Japan, China, and South Korea all conduct military exercises in the East China Sea.
Did You Know?
- The East China Sea is one of the Four Seas of Chinese literature, each corresponding to a cardinal direction.
- Until 2004, Japanese official documents referred to the sea as 東支那海 (Higashi Shina Kai), before switching to 東シナ海.
- American whaleships cruised for right whales in the East China Sea between 1849 and 1892.
- The maximum depth of the East China Sea, 2,716 meters, is reached in the Okinawa Trough.
- The Chunxiao gas field, discovered by China in 1995, lies within China's claimed EEZ but near Japan's proposed median line.
Frequently Asked Questions
Who is East China Sea?
East China Sea is a marginal sea tucked into the Western Pacific, sitting directly offshore from eastern China. Its perimeter is shared by South Korea, Japan, Taiwan, and China, with the Ryukyu Islands forming the southeastern boundary.
What are East China Sea's powers/role?
It acts as a critical waterway stitching together the Sea of Japan, the South China Sea, and the Philippine Sea through a chain of straits. The Yangtze River is its single largest freshwater source, and the body of water carries an official International Hydrographic Organization designation.
How does East China Sea's story end?
Its deepest chapter unfolds in the Okinawa Trough, where the floor drops to 2,716 metres before the waters merge into the open Philippine Sea. Past that point the distinct identity of the sea dissolves into the broader Pacific basin.
Why is East China Sea important?
Covering roughly 1.25 million square kilometres with an average depth of only about 350 metres, it is one of the most strategically shallow and heavily trafficked marginal seas in the region. Its position makes it a linchpin for fisheries, container shipping, and energy routes among the four bordering nations.
What is East China Sea's stats sheet?
Area: ~1,249,000 km²; average depth: ≈350 m; maximum depth: 2,716 m (Okinawa Trough); bordering territories: China, Japan, South Korea, Taiwan; dominant river inflow: Yangtze; naming authority: International Hydrographic Organization.
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