The World's Seas: IHO's 51 Divisions Across 6 Ocean Basins

The International Hydrographic Organization (IHO) recognizes 51 named seas, gulfs, and bays within the world's five oceans. Here's the structured breakdown:

1. Arctic Ocean (9 seas)

• Barents, Beaufort, Chukchi, East Siberian, Kara, Laptev, Lincoln, Norwegian, Wandel

2. North Atlantic Ocean (14 seas/gulfs)

• Azores Sea, Baffin Bay, Baltic Sea, Bay of Biscay, Caribbean Sea, Celtic Sea, Davis Strait, Greenland Sea, Gulf of Mexico, Hudson Bay, Irish Sea, Labrador Sea, Mediterranean Sea, North Sea

3. South Atlantic Ocean (4 seas)

• Argentine Sea, Drake Passage, Gulf of Guinea, Weddell Sea

4. Indian Ocean (7 seas)

• Andaman Sea, Arabian Sea, Bay of Bengal, Great Australian Bight, Gulf of Oman, Mozambique Channel, Red Sea

5. North Pacific Ocean (8 seas)

• Bering Sea, East China Sea, Gulf of Alaska, Japan Sea, Philippine Sea, Sea of Okhotsk, South China Sea, Yellow Sea

6. South Pacific Ocean (7 seas)

• Amundsen Sea, Bellingshausen Sea, Coral Sea, East China Sea (shared), Ross Sea, Tasman Sea

Note: Some seas span boundaries (East China Sea in both N/S Pacific). Definitions evolve (IHO 2002 draft unpublished; 1953 edition remains official). Seas regulate climate, concentrate biodiversity, focus fisheries, and define geopolitics.