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Does Our Planet Have Four Oceans, or Five?

Last Modified Date: February 20, 2024

If you can recall your elementary school geography lessons, you probably learned that our planet has four oceans: the Atlantic, Pacific, Arctic, and Indian. (Actually, those oceans are simply regions of our planet’s interconnected world ocean, but that’s another story.)

Yet in 2021, National Geographic announced that it was officially recognizing a fifth ocean, the Southern Ocean, which stretches from the coast of Antarctica up to 60 degrees south latitude. For years, many scientists and geographers had argued that the Southern Ocean should be classified as a separate ocean, though others countered that it was simply the coldest, southernmost parts of the Atlantic, Pacific, and Indian Oceans, which it borders. Nor could they agree on a name—the Antarctic Ocean and the Austral Ocean had been among the other suggestions.

In 2021, National Geographic cartographers officially recognized the Southern Ocean as distinct from the other four oceans; it stretches from Antarctica to 60° S latitude.

Yet there is more that makes the Southern Ocean unique than simply its location. The Southern Ocean is home to the Antarctic Circumpolar Current, which moves clockwise around Antarctica, essentially keeping the region cold and defining its unique ecological niche. Numerous marine creatures thrive in the cold of the Southern Ocean, many of which feed on the hugely abundant Antarctic krill at the bottom of the ecosystem’s food chain. You’ll find minke, orca, and humpback whales; leopard seals; and emperor penguins in and around the Southern Ocean.

While some may argue that designating and naming a fifth ocean is just semantics (after all, there’s really only one world ocean), many biologists and climate scientists applaud National Geographic’s move to recognize the Southern Ocean. After all, Antarctica is currently one of the fastest warming regions of our planet, an issue that affects not only the continent’s unique ecosystems but also weather patterns and the global climate as a whole. Making the Southern Ocean “official,” and including it on maps and educational resources, could help raise awareness of the threats facing this special ecological region.

Not just another ocean:

National Geographic has been making maps of the world’s oceans since 1915. The organization’s recognition of the Southern Ocean in 2021 came on June 8, which is World Oceans Day.

While the National Oceanic and Atmospheric Administration (NOAA) recognized the Southern Ocean in 1999, the member countries of the International Hydrographic Organization were unable to agree on its name and boundaries until 2021.

Unlike the other oceans, which are primarily separated by landmasses, the Southern Ocean’s boundary is marked by the Arctic Circumpolar Current (ACC). The ACC is the strongest current on the planet, moving up to 182 million cubic meters of water per second in an eastward direction.

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