Indonesia dwarfs Oceania: about 1,872,242 km² km² against 8,600,000 km² km². At true size Indonesia is about 4.6× larger — the whole of Oceania fits into Indonesia roughly 4 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.
Indonesia fits 4× into Oceania.