# Where Does One Ocean End and Another Begin? **URL:** \ **Category:** Factual Questions\ **Created:** [October 1, 2009, 3:27am UTC](https://boards.straightdope.com/t/where-does-one-ocean-end-and-another-begin/512202 "2009-10-01T03:27:06Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![taffygirl](https://avatars.discourse-cdn.com/v4/letter/t/b5a626/32.png) [@taffygirl](https://boards.straightdope.com/u/taffygirl)\ **Post date:** [October 1, 2009, 3:27am UTC](https://boards.straightdope.com/t/where-does-one-ocean-end-and-another-begin/512202/1 "2009-10-01T03:27:06Z")
This is something I’ve always wondered about. Look on any world map, and you can see that the oceans are really one huge body of water. How is it determined exactly where, say, the Indian Ocean ends and the Pacific begins, or where, exactly, the Pacific meets the Atlantic at the southern tip of South America? Is it by latitude and longitude? If I stand at the southernmost tip of Chile (or Argentina), could I scoop up one handful of two oceans? ---
**Author:** ![Derleth](https://avatars.discourse-cdn.com/v4/letter/d/b9e5f3/32.png) [@Derleth](https://boards.straightdope.com/u/Derleth)\ **Post date:** [October 1, 2009, 3:46am UTC](https://boards.straightdope.com/t/where-does-one-ocean-end-and-another-begin/512202/2 "2009-10-01T03:46:08Z")
Good question. Sadly, there is no answer: The oceans are merely names for very general regions of a continuous body of water that doesn’t know or care what humans think. If you want to go to Tierra del Fuego and claim you can touch two oceans at once, go for it. Nobody will be able to say you’re a liar. ---
**Author:** ![Horatio\_Hellpop](https://avatars.discourse-cdn.com/v4/letter/h/e5b9ba/32.png) [@Horatio\_Hellpop](https://boards.straightdope.com/u/Horatio_Hellpop)\ **Post date:** [October 1, 2009, 12:11pm UTC](https://boards.straightdope.com/t/where-does-one-ocean-end-and-another-begin/512202/3 "2009-10-01T12:11:37Z")
The [CIA World Factbook](https://www.cia.gov/library/publications/the-world-factbook/) demarcates the oceans pretty specifically. They draw the lines differently than I would; they include the Mediterranean and Black Seas as part of the Atlantic, but consider all water south of the Antarctic Circle to be something called “The Southern Ocean.” ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [October 1, 2009, 12:58pm UTC](https://boards.straightdope.com/t/where-does-one-ocean-end-and-another-begin/512202/4 "2009-10-01T12:58:18Z")
The people who define this sort of thing are the [International Hydrographic Organization](http://www.iho-ohi.net/english/home/). The IHO publishes a document called _Limits of Oceans and Seas_, which you can download from [this page](http://www.iho.shom.fr/PUBLICATIONS/IHO_Download.htm) (ref S-23). ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [October 1, 2009, 1:04pm UTC](https://boards.straightdope.com/t/where-does-one-ocean-end-and-another-begin/512202/5 "2009-10-01T13:04:32Z")
To answer your question about Tierra del Fuego, the IHO says this: > [@](#): > > The Southern boundary line between the South Atlantic and South Pacific Oceans is the meridian of Cape Horn (67º16’W) The latest edition seems to be dated 1953, so a lot of the country names are out of date. ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [October 1, 2009, 1:21pm UTC](https://boards.straightdope.com/t/where-does-one-ocean-end-and-another-begin/512202/6 "2009-10-01T13:21:56Z")
> [@Krokodil](#): > > The [CIA World Factbook](https://www.cia.gov/library/publications/the-world-factbook/) demarcates the oceans pretty specifically. They draw the lines differently than I would; they include the Mediterranean and Black Seas as part of the Atlantic, but consider all water south of the Antarctic Circle to be something called “The Southern Ocean.” What other ocean would the Mediterreanean and Black seas be part of? 😕 ---
**Author:** ![davekhps](https://avatars.discourse-cdn.com/v4/letter/d/a5b964/32.png) [@davekhps](https://boards.straightdope.com/u/davekhps)\ **Post date:** [October 1, 2009, 4:56pm UTC](https://boards.straightdope.com/t/where-does-one-ocean-end-and-another-begin/512202/7 "2009-10-01T16:56:06Z")
> [@Really\_Not\_All\_That\_Bright](#): > > What other ocean would the Mediterreanean and Black seas be part of? 😕 It wouldn’t be part of an ocean, they’re seas. Of course, the Med (like the Baltic) connects to the Atlantic, but the circulation is so low as to be negligible. Taken to the extremes, the Atlantic Ocean is part of the Great Lakes because the St. Lawrence River connects them to the ocean. So, technically-- Atlantic Ocean. Practically-- of course not. ---
**Author:** ![Really\_Not\_All\_That\_Bright](https://avatars.discourse-cdn.com/v4/letter/r/e8c25b/32.png) [@Really\_Not\_All\_That\_Bright](https://boards.straightdope.com/u/Really_Not_All_That_Bright)\ **Post date:** [October 1, 2009, 5:38pm UTC](https://boards.straightdope.com/t/where-does-one-ocean-end-and-another-begin/512202/8 "2009-10-01T17:38:23Z")
All non-inland seas are part of oceans, regardless of circulation. The Great Lakes are fresh water. It’s like arguing that country X isn’t part of continent Y because it’s a country. ---
**Author:** ![Colibri](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/colibri/32/1841_2.png) [@Colibri](https://boards.straightdope.com/u/Colibri)\ **Post date:** [October 1, 2009, 6:50pm UTC](https://boards.straightdope.com/t/where-does-one-ocean-end-and-another-begin/512202/9 "2009-10-01T18:50:42Z")
> [@davekhps](#): > > It wouldn’t be part of an ocean, they’re seas. > > Of course, the Med (like the Baltic) connects to the Atlantic, but the circulation is so low as to be negligible. Taken to the extremes, the Atlantic Ocean is part of the Great Lakes because the St. Lawrence River connects them to the ocean. > > So, technically-- Atlantic Ocean. Practically-- of course not. The Mediterranean, Black, and Baltic Seas are all connected to the Atlantic via sea level, salt water connections, thus they can be considered part of the Atlantic. Even if there is limited circulation, it’s still there. The Great Lakes are freshwater, are not at sea level, and are connected to the Atlantic via a freshwater river through which there is no circulation. There is really no reason to consider them part of the Atlantic. ---
**Author:** ![Colophon](https://avatars.discourse-cdn.com/v4/letter/c/f05b48/32.png) [@Colophon](https://boards.straightdope.com/u/Colophon)\ **Post date:** [October 1, 2009, 7:42pm UTC](https://boards.straightdope.com/t/where-does-one-ocean-end-and-another-begin/512202/10 "2009-10-01T19:42:28Z")
> [@davekhps](#): > > It wouldn’t be part of an ocean, they’re seas. All seas (except inland seas like the Caspian) are part of an ocean. It’s not an either/or issue. Seas are subdivisions of oceans. Saying the Mediterranean is a sea and therefore not part of the Atlantic is like saying Chicago isn’t part of the USA because it’s a city, not a country.