"Wenn ich die See seh', brauch' ich kein Meer mehr." ;-) In general you can use both terms 'die See' and 'das Meer' without being concerned about differences. It does not matter. There are, however, some idiomatic expressions and composite words, where you can't mix them. e.g. there's 'Wattenmeer' but no 'Wattensee' and 'Tiefsee' but no 'Tiefmeer'. And when someone is telling you 'Ich fahre zum Meer' (he's changing his location so that he's approaching the sea) it's completely different from 'Ich fahre zur See' (he's a seaman).

DIE See/DER Ozean/DAS Meer = the ocean/the sea DER See = the lake Sorry about this extra use for "See".

Ich fahre zum See = I´m going to the lake KOMMENTARFUNKTION ! BITTE !