East Sea or Eastern Sea may refer to:

• East China Sea, a marginal sea east of China, where it is called Dōnghǎi (东海/東海) in Chinese, meaning "East Sea"
  • East Sea (Chinese literature), one of the Four Seas, a literary name for the boundaries of China
• South China Sea, a marginal sea south of China and east and south of Indochina, called Biển Đông in Vietnamese, meaning "East Sea"
• Sea of Japan, a marginal sea between the Korean Peninsula, Russia and the Japanese archipelago, called Donghae (Korean: 동해; Hanja: 東海; East Sea) in South Korea, and Chosŏn Tonghae (Korean: 조선동해; Hancha: 朝鮮東海; Korean East Sea) in North Korea.
  • Sea of Japan naming dispute
• Baltic Sea, called "East Sea" in various languages
• Dead Sea, a salt lake east of Israel, as used in the Bible (Joel 2:20; Ezek. 47:18)
• Mare Orientale, Latin for "Eastern Sea", on the Moon
• Atlantic Ocean, also referred to as the East Sea or Eastern Sea in poetry and other uses in North America
• Pacific Ocean, called the East Sea in poetry and other uses from Australia, New Zealand, China and Japan
• Indian Ocean, earlier called the "Eastern Ocean" or "Eastern Sea"
• Eastern Sea, the eastern ocean of Middle-earth in J. R. R. Tolkien's fiction

• East Sea Campaign, a naval operation of the Vietnam War
• East Sea Fleet
• Donghai Bridge
• South Sea (disambiguation)
• North Sea (disambiguation)
• West Sea (disambiguation)
• 東海, the Chinese script for "East Sea"
  • Donghae (disambiguation), Korean romanization
  • Tokai (disambiguation), Japanese romanization
  • Donghai (disambiguation), Pinyin romanization
  • Tunghai (disambiguation), Wade–Giles romanization