Africa dwarfs Oceania: about 30,370,000 km² km² against 8,600,000 km² km². At true size Africa is about 3.5× larger — the whole of Oceania fits into Africa roughly 3 times.
The old Mercator map treated both about equally (1× vs 1× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Oceania fits 3× into Africa.