If you’d asked National Geographic a week ago how many oceans there are, they would have told you “four.” There’s the Atlantic and the Pacific Oceans, of course, as well as the somewhat smaller Indian Ocean, and the oft-overlooked Arctic Ocean. But as of June 8, 2021 — “World Oceans Day” — National Geographic’s team of geographers has formally recognized a fifth ocean: the Southern Ocean.

The Southern Ocean is essentially the counterpart to the Arctic Ocean; it’s a roughly circular ocean encircling the entire continent of Antarctica. Seth Sykora-Bodie, a National Geographic Explorer, describes the Southern Ocean as a unique place: “Anyone who has been there will struggle to explain what’s so mesmerizing about it, but they’ll all agree that the glaciers are bluer, the air colder, the mountains more intimidating, and the landscapes more captivating than anywhere else you can go.”

But National Geographic is not the first entity to recognize the Southern Ocean; many scientists had already advocated for giving the Southern Ocean its own “ocean” label. Yet other geographers still consider the water around Antarctica to be a southern extension of the Atlantic, Pacific, and Indian Oceans, rather than its own unique body. In weighing the evidence, Nat Geo ultimately decided to side with the scientists who advocated for labeling the Southern Ocean as a fifth official ocean. So, after all these years, what led to that decision?

National Geographic formally recognized the “Southern Ocean” around Antarctica as Earth's fifth ocean

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