In the concluding remarks to the account of his explorations in Australia, Edward John Eyre begins to discuss the nature of the interior of the Australian continent. Is it a desert, or might there be an inland sea? An inland sea had been the subject of much speculation over 50 years or more and was further fuelled by the drainage of the eastern rivers towards the centre of the continent. Eyre's experience of the northern regions of South Australia revealed a largely flat and dreary waste. Unlike his friend and fellow explorer Charles Sturt, Eyre does not believe in an inland sea.

Matthew Flinders had hypothesised about an inland sea in the Introduction to A Voyage to Terra Australis ... and the evidence of the inland flowing rivers of New South Wales had added to the theory. Charles Sturt had determined where most of the rivers flowed when he discovered the River Darling and later the River Murray, and had sailed down this river to the sea in 1829/30. However Sturt had also watched the flight of birds during this expedition, and later when he settled in South Australia: he believed that where their flight paths intersected he would find an inland sea. On his expedition of 1844/46 he hoped to find it. However his friend Edward Eyre had explored north from Spencer Gulf and had only encountered barren land and interminable salt lakes. He did not believe in an inland sea. It would be another 20 years or so before the theory was laid to rest.