In reality, there is just one ocean.
However, I understand the confusion as of late on the geographic names applied to different sections of this ocean ecosystem. While we lost a planet (Pluto), we gained an ocean! In 2000, the International Hydrographic Organization named this new ocean the Southern Ocean. Basically, it is the southern equivalent of the Arctic Ocean, except a little bit larger in sprawling space. So, there are 5 oceans.
Here they are in a listing of greatest to least in square miles:
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