What is the collective name for the seas of Indonesia?
I've always known it as the Maritime Continent, as in,

Neale and Slingo (2003) The Maritime Continent and Its Role in the Global Climate: A GCM Study, J. Clim, doi:10.1175/1520-0442(2003)016%3C0834:TMCAIR%3E2.0.CO;2

But that has an atmospheric perspective; it refers to the ocean and the land, because they're both important for the meteorology of the region.  There may be another name for just the watery bits in between the land.