There is a cluster of submerged reefs in the northern East China Sea. These include:
The dispute between China and Japan concerns natural gas. The People's Republic of China (PRC) recently discovered that there exists an undersea natural gas field in the East China Sea, part of the field lies within the Chinese EEZ while the remaining lies on the disputed EEZ between Japan and the PRC. Under the United Nation's Law of the Sea, PRC claims the disputed ocean territory as its own Exclusive Economic Zone (EEZ) due to its being part of PRC's natural extension of its continental shelf, while Japan claims the disputed ocean territory as its own EEZ because it is within 200 nautical miles (370 km) from Japan's coast.
China has set up the Chunxiao gas field, which is located more than 4 km inside the Chinese side of the EEZ boundary claimed by Japan and is within China's own EEZ, to extract the natural gas. Japan maintains that although the Chunxiao gas field rigs are on China's side of a median line that Tokyo regards as the two sides' sea boundary, they may tap into a field that stretches into the disputed area. Japan therefore seeks a share in the natural gas resources.
The dispute between China and South Korea concerns Socotra Rock, a submerged reef on which South Korea has constructed a scientific research station. While neither country claims the rock as territory, China has objected to Korean activities there as a breach of its EEZ rights.