Explanation: The International Hydrographic Organization (IHO) is responsible for the formal designation of the East China Sea, which it classifies as a marginal sea of the Western Pacific Ocean, distinct from China's internal nomenclature of 'East Sea'.

Explanation: Contrary to the statement, the East China Sea is predominantly shallow, with nearly three-fourths of its area having depths less than 200 meters, as indicated by hydrographic data.

Explanation: The East China Sea is bordered to the south by Taiwan and to the east/southeast by Kyushu and the Ryukyu Islands, while its western border is mainland China, not Kyushu.

Explanation: The connection between the East China Sea and the Yellow Sea in the north is indeed defined by an imaginary line stretching from Jeju Island, South Korea, to Qidong at the Yangtze River estuary.

Explanation: The IHO's definition of the East China Sea's northern limit precisely follows the described geographical points, from Nomo Saki in Kyushu to Hunan Kan and then along the specified parallel to the mainland.

Explanation: The Yangtze River, not the Yellow River, is identified as the largest river flowing into the East China Sea, playing a crucial role in the sea's hydrology and ecology.

Explanation: Historical records indicate that American whaleships primarily hunted right whales in the East China Sea between 1849 and 1892, not blue whales.

Explanation: In Chinese astronomy, the East China Sea, or 'Donghai,' is indeed possibly represented by the star Eta Serpentis, which forms part of the 'Left Wall' asterism within the 'Heavenly Market enclosure' constellation system.

Explanation: The East China Sea connects to the South China Sea via the Taiwan Strait. The Tokara Strait and Miyako Strait, conversely, link the East China Sea to the Philippine Sea through the Ryukyu Islands.

Explanation: The IHO's definition of the East China Sea's southern limit precisely matches the description, extending from Fuki Kaku to Kiushan Tao, then to Haitan Tao's southern point, and westward to the Fukien coast.

Explanation: The East China Sea has an average depth of 350 meters, not 1,150 meters, and its maximum depth of 2,716 meters is found in the Okinawa Trough, not the Yellow Sea Trough.

Explanation: The International Hydrographic Organization (IHO) is the international body responsible for the formal designation and standardization of names for maritime geographical features, including the East China Sea.

Explanation: The East China Sea spans an approximate area of 1,249,000 square kilometers (482,000 sq mi), making it a significant marginal sea of the Western Pacific Ocean.

Explanation: The island of Taiwan serves as the southern geographical boundary of the East China Sea, as delineated by international hydrographic descriptions.

Explanation: The East China Sea connects to the Sea of Japan in the northeast through the Korea Strait, facilitating maritime passage between these two significant bodies of water.

Explanation: The International Hydrographic Organization (IHO) explicitly defines the western limit of the East China Sea as the mainland of China, forming a clear geographical boundary.

Explanation: The Yangtze River (Chang Jiang) is definitively identified as the largest river that discharges into the East China Sea, significantly influencing its hydrological and ecological characteristics.

Explanation: Until 2004, the Japanese officially referred to the East China Sea as Higashi Shina Kai (東支那海), meaning 'East Shina Sea,' before the Foreign Ministry switched to a different character usage with the same pronunciation.

Explanation: American whaleships were actively involved in hunting right whales in the East China Sea for a defined period spanning from 1849 to 1892, marking a notable era of commercial whaling operations in these waters.

Explanation: In Chinese astronomy, the star Eta Serpentis is possibly identified with the East China Sea (Donghai), forming part of the 'Left Wall' asterism within the 'Heavenly Market enclosure'.

Explanation: The East China Sea has an average depth of 350 meters (1,150 ft), although much of its area is shallower, and it reaches significantly greater depths in certain troughs.

Explanation: The countries and territories bordering the East China Sea, listed clockwise from north, are South Korea, Japan, Taiwan, and China. Vietnam is not among these directly bordering entities.

Explanation: The East China Sea connects to the Philippine Sea through several gaps located between the Ryukyu Islands, including notable passages such as the Tokara Strait and Miyako Strait.

Explanation: The East China Sea reaches its maximum depth of 2,716 meters (8,911 ft) within the Okinawa Trough, a significant geological feature of the seabed.

Explanation: Tong Island is explicitly mentioned as a notable island located within the East China Sea, alongside various submerged reefs in the northern part of the sea.

Explanation: In Chinese, the East China Sea is referred to as 'Dōng Hǎi' (東海), which translates to 'East Sea,' and holds significant cultural resonance as one of the revered Four Seas in Chinese literature.

Explanation: The discovery of the Chunxiao gas field by the PRC in 1995 led to heightened disputes with Japan, not South Korea, due to concerns over resource exploitation in contested waters.

Explanation: The dispute over the Chunxiao gas field arises because the rigs are in China's undisputed EEZ, but Japan fears they may tap into reserves extending into the disputed area, not because Japan claims the rigs are in its undisputed EEZ.

Explanation: The Xihu Sag area gas fields, including Chunxiao, indeed commenced commercial operations in 2006 and are estimated to hold proven natural gas reserves of 364 billion cubic feet.

Explanation: In 2008, China and Japan did agree to jointly develop the Chunxiao gas fields; however, they have since been unable to finalize the specific details and methods for executing this joint development plan.

Explanation: The People's Republic of China (PRC) discovered the Chunxiao gas field in 1995, a significant event that led to heightened disputes with Japan over energy resources in the East China Sea.

Explanation: Japan's concern regarding the Chunxiao gas field, even with rigs in China's undisputed EEZ, is the apprehension that the field's operations might extract natural gas from reserves that extend beneath the seabed into the disputed maritime area.

Explanation: The gas fields located in the Xihu Sag area of the East China Sea, which include several significant fields, are estimated to hold proven natural gas reserves totaling 364 billion cubic feet (BCF).

Explanation: In 2008, China and Japan formally agreed to jointly develop the Chunxiao gas fields; however, this agreement has remained largely unimplemented due to their subsequent inability to reach a consensus on the specific methods and details for its execution.

Explanation: Socotra Rock is indeed a submerged reef in the northern East China Sea and a subject of an EEZ dispute, but this dispute is primarily between the People's Republic of China and South Korea, not Japan.

Explanation: Beyond natural gas fields, China and Japan have engaged in disputes primarily concerning island ownership in the East China Sea, rather than fishing rights or environmental protection, leading to diplomatic and civilian tensions.

Explanation: The core issue of the EEZ dispute between the PRC and South Korea centers on Socotra Rock, a submerged reef where South Korea has built a research station, which China views as a breach of its EEZ rights, rather than the ownership of Tong Island.

Explanation: Tong Island is mentioned as a notable island in the East China Sea, while Socotra Rock is the submerged reef in the northern East China Sea that is a subject of an EEZ dispute between China and South Korea.

Explanation: Socotra Rock, also known as Suyan Rock or Ieodo, is the specific submerged reef in the northern East China Sea that is the subject of an ongoing EEZ dispute between the People's Republic of China and South Korea.

Explanation: In addition to disagreements over natural gas fields, China and Japan have also engaged in significant disputes concerning island ownership in the East China Sea, leading to diplomatic protests and civilian demonstrations.

Explanation: The core issue of the EEZ dispute between the People's Republic of China (PRC) and South Korea revolves around Socotra Rock, a submerged reef where South Korea has established an ocean research station, which the PRC considers a breach of its EEZ rights.

Explanation: In its littoral operations sphere, including the East and South China Seas, China's navy actually possesses more naval vessels than the US Navy, reflecting its significant investment in regional maritime capabilities.

Explanation: US Presidents Obama and Trump indeed shared a strategic priority to expand the US sphere of influence in the Pacific Ocean, aiming to counter China's growing strength and ensure future readiness.

Explanation: The primary role of the Chinese Navy in the East China Sea is to uphold China's ownership of contested territories and safeguard its maritime routes, particularly concerning issues like the Senkaku (Diaoyutai) Islands, rather than conducting joint drills with allies.

Explanation: China's increased naval patrols and surveillance in the East China Sea are indeed a demonstration of its naval involvement, reflecting its strategic priorities to defend territorial claims and project strength in the region.

Explanation: The Japanese Maritime Self-Defense Force (MSDF) is of paramount importance for Japan's defense and maritime security in the East China Sea, particularly concerning the Senkaku (Diaoyutai) Islands conflict, indicating a primary focus on territorial defense rather than solely humanitarian aid.

Explanation: Japan enhances its maritime capabilities by increasing naval patrols and surveillance in the East China Sea to protect its territorial rights and monitor regional activities, not by reducing them.

Explanation: Taiwan's maritime actions in the East China Sea are not as extensive as those of China and Japan; while it maintains a Coast Guard presence, its overall involvement is influenced by territorial disputes and strategic concerns, not a comparable naval fleet size.

Explanation: Tensions over the Senkaku (Diaoyutai) Islands indeed significantly impact Taiwan's security and necessitate continuous diplomatic communication with all relevant parties to ensure maritime safety and regional stability.

Explanation: In addition to China and Japan, Taiwan and South Korea also conduct military exercises in the East China Sea, demonstrating their respective national defense capabilities and presence in the region.

Explanation: The Chinese Navy's activities in the East China Sea indeed play a crucial role in shaping regional security dynamics, influencing the naval strategies of neighboring countries and impacting maritime cooperation initiatives, as well as highlighting major power competition.

Explanation: In its immediate maritime vicinity, including the East and South China Seas, China's navy currently possesses a greater number of naval vessels than the US Navy, indicating a significant regional military presence.

Explanation: A shared strategic goal for both US Presidents Obama and Trump was to expand the US sphere of influence in the Pacific Ocean, primarily to counter China's increasing military and economic strength and ensure future readiness.

Explanation: The Chinese Navy's primary role in the East China Sea is to assert and uphold China's ownership of contested territories, such as the Senkaku (Diaoyutai) Islands, and to ensure the security of its vital maritime routes.

Explanation: China demonstrates its naval involvement in the East China Sea through the deployment of naval ships and the regular conduct of maritime patrols, reflecting its strategic priorities to defend territorial claims and project strength.

Explanation: The Japanese Maritime Self-Defense Force (MSDF) is of paramount importance for Japan's defense and maritime security in the East China Sea, particularly in addressing the ongoing Senkaku (Diaoyutai) Islands conflict.

Explanation: Japan enhances its maritime capabilities in the East China Sea through increased naval patrols and surveillance, a strategy aimed at protecting its territorial rights and monitoring regional activities, thereby upholding international law.

Explanation: Japan's Maritime Self-Defense Force (MSDF) plays a broader role in regional security cooperation by actively participating in joint naval drills with allies and partners throughout the Indo-Pacific region, which serves to strengthen alliances and improve interoperability.

Explanation: Taiwan's involvement in the East China Sea is significantly influenced by its territorial disputes, particularly concerning the Senkaku (Diaoyutai) Islands, its broader strategic concerns, and the complex dynamics of its cross-strait relations with China.

Explanation: The source explicitly states that Taiwan, Japan, China, and South Korea all conduct military exercises in the East China Sea; North Korea is not mentioned as a participant in these exercises.

Explanation: Taiwan maintains a Coast Guard presence in the East China Sea primarily for the purpose of patrolling its territorial waters and effectively managing various maritime incidents that may arise, reflecting its strategic concerns and territorial disputes.