X-post from /ELI5 because I had no idea this subreddit was a thing.
I was looking at the Theatrum Orbis Terrarum over on TIL, and I was wondering, why is it that, even when having a reasonably detailed idea of what Indonesia was like, it took Europeans so much longer to find Australia? Indonesia and Australia are not very far apart! You can cross from Papau New Guinea to Queensland in a canoe for goodness sake. How was it that the Indonesian islands were so well known, and it still took hundreds of years for anyone to think to sail south a little bit more? Was is because of some kind of difficulty with the seas there, or did Europeans just not care to look at that point?
Part of the reason might be that they did "discover" Australia fairly early - I believe the Dutch made landfall along the West Australian coast in the late 1500s or early 1600s. With that in mind, think of the context of the discovery - the Western Australian coast is for the most part a dry, desolate and barren land, and not really conducive to prospects for long term settlement. The east coast of Australia was better suited - plenty of greenery, rich in easily accessible woodlands.