Looking through the 'other languages' links it seems that the sea is called the South China Sea in nearly every language that is written in the latin or cyrillic alphabets.
Alright, since this seems to be a hard thing for some to grasp...
Some Britishs use the word "loo" for bathroom.
Almost all Americans use the word bathroom/toilet/restroom/lavatory.
Are you going to tell the British person that he is wrong and silly for using the word "loo"?