Namibia dwarfs Oceania: about 824,750 km² km² against 8,600,000 km² km². At true size Namibia is about 10.4× larger — the whole of Oceania fits into Namibia roughly 10 times.
The old Mercator map treated both about equally (1.2× vs 1× inflation), so at least their relative sizes were preserved — even if both were drawn at the wrong absolute scale.
Namibia fits 10× into Oceania.