Oceania dwarfs South Africa: about 8,600,000 km² km² against 1,221,609 km² km². At true size Oceania is about 7× larger — the whole of South Africa fits into Oceania roughly 7 times.
The old Mercator map treated both about equally (1× vs 1.3× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
South Africa fits 7× into Oceania.