How is the total area of the world's oceans 361 million square kilometres? I can't see how the five individuals ones add to that.

When I Google how many squared km is this/that ocean, I get

enter image description here

When add the areas of those five oceans, 106.5+161.8+70.56+14.06+20.33

enter image description here

I get 373.25 million sq km.

Yet the world ocean, which should be the sum of the 5 oceans, is 361 million sq km.

If I try this site https://www.infoplease.com/world/world-geography/oceans-and-seas

It says Pacific = 155.557, Atlantic = 76.76, Indian = 68.556, Southern =2 0.327, Arctic = 14.056

155.557 + 76.76 + 68.556 + 20.327 + 14.056 = 335 sq km

So, also, not 361 million square km

Any idea why the figures differ and what are the correct figures?

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    $\begingroup$ It is a mathematical evidence there is some kind of mistake. The sources may come from different studies. It migth be simple to delimitate southern ocean from a certain latitude, but for other limits there is sure controversy and so. $\endgroup$ – user12525 Jul 28 '18 at 14:27
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    $\begingroup$ At the second link you have also data for mediterranian , caribean etc. you have not added them to the sume that gives 335, but gives less than 373 too $\endgroup$ – user12525 Jul 28 '18 at 14:29
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    $\begingroup$ Since the boundaries between the oceans are at best fuzzy, it shouldn't be surprising that different sources add up to different numbers. Since you are relying on unreliable sites (even wikipedia is an unreliable site in this regard), it shouldn't be surprising at all that you are getting contradictory results. $\endgroup$ – David Hammen Jul 28 '18 at 23:22
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    $\begingroup$ An "ocean" is a loosely defined term. Unlike countries that mostly have well defined borders, oceans are defined according to a somewhat vague area. $\endgroup$ – Gimelist Jul 29 '18 at 10:41
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    $\begingroup$ Currently NOAA says there is only one ocean @Barry Carter. oceanservice.noaa.gov/facts/howmanyoceans.html At the comments of the question I linked you can read a great: "I once heard a lovely description of the world's seas (by a polar scientist) as "One ocean with three big estuaries" :-)" $\endgroup$ – user12525 Jul 29 '18 at 11:43

Commenter Universal Learner points out "Currently NOAA says there is only one ocean"


and "At the comments of the question I linked you can read a great: "I once heard a lovely description of the world's seas (by a polar scientist) as "One ocean with three big estuaries" ;-) "

While there is only one global ocean, the vast body of water that covers 71 percent of the Earth is geographically divided into distinct named regions. The boundaries between these regions have evolved over time for a variety of historical, cultural, geographical, and scientific reasons.

Historically, there are four named oceans: the Atlantic, Pacific, Indian, and Arctic. However, most countries - including the United States - now recognize the Southern (Antarctic) as the fifth ocean. The Pacific, Atlantic, and Indian are known as the three major oceans.

The Southern Ocean is the 'newest' named ocean. It is recognized by the U.S. Board on Geographic Names as the body of water extending from the coast of Antarctica to the line of latitude at 60 degrees South. The boundaries of this ocean were proposed to the International Hydrographic Organization in 2000. However, not all countries agree on the proposed boundaries, so this has yet to be ratified by members of the IHO. The U.S. is a member of the IHO, represented by the NOS Office of Coast Survey.

And they have a graphic saying 1 world ocean. Historically 4 basins. Now 5 basins. And that the boundaries aren't agreed upon by all countries. Though that text refers to a basin as an ocean, so their terminology doesn't quite match their graphic.

| improve this answer | |
  • $\begingroup$ Do we include the landlocked Caspian Sea (371,000 km^2/ 143,200 mi^2)) as part of the ocean? Or even the very nearly landlocked Black Sea? $\endgroup$ – jamesqf May 25 '19 at 18:40

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