What's the difference between 海洋 and 大洋?


According to my dictionary they both mean "ocean", but I guess there is a
reason for both words to exist. Am I right ?




海洋 is simply a technical/scientific version of 海. In scientific contexts, 大洋
specifically refers to the five [**global
oceans**](https://en.wikipedia.org/wiki/World_Ocean) on the earth, namely 太平洋
(The Pacific Ocean), 大西洋 (The Atlantic Ocean), インド洋 (The Indian Ocean), 北極海
(The Arctic Ocean), and 南極海 (The Southern Ocean). Imagine 大洋 is a oceanic
version of 大陸 (continent). See [this Wikipedia
article](https://ja.wikipedia.org/wiki/%E5%A4%A7%E6%B4%8B).

Outside scientific contexts, 大洋 is not a common word. It's possible to use it
simply in the sense of "big ocean", but I think 大海 is much more commonly used
for this purpose.




海洋 is simply a technical/scientific version of 海. In scientific contexts, 大洋
specifically refers to the five [**global
oceans**](https://en.wikipedia.org/wiki/World_Ocean) on the earth, namely 太平洋
(The Pacific Ocean), 大西洋 (The Atlantic Ocean), インド洋 (The Indian Ocean), 北極海
(The Arctic Ocean), and 南極海 (The Southern Ocean). Imagine 大洋 is a oceanic
version of 大陸 (continent). See [this Wikipedia
article](https://ja.wikipedia.org/wiki/%E5%A4%A7%E6%B4%8B).

Outside scientific contexts, 大洋 is not a common word. It's possible to use it
simply in the sense of "big ocean", but I think 大海 is much more commonly used
for this purpose.

