Search for the inland sea

The next chapter in the history of early land exploration in Australia is marked by two major obsessions - solving the mystery of the western river system and searching for the mythical inland sea.

Over a thirty year period, surveyors George Evans, John Oxley, Charles Sturt and Thomas Mitchell were employed to make a series of expeditions into the interior of the continent. Their efforts allowed the gradual filling in of previously blank spaces on the Australian map.

View all surveys by J. Arrowsmith in further detail 

Investigating the lifetime achievements of these men reveals some of the most significant contributions made by colonial explorers in defining the shape of inland Australia.

Mapping the interior

The successful crossing of the Blue Mountains marked the end of the first phase of exploration. With a feasible inland route now available, thoughts turned to opening up the interior to grazing and settlement.

For the next few decades the focus of exploration would lie in solving the mysteries of the western rivers and pursuing the enticing possibility that they flowed into a vast inland sea. The colony's surveyors soon fanned out in all directions, crossing the plains and following every stream, in the hope of finding Australia's own Amazon River.

• View the proposed mythical sea by Thomas Maslen

After surveying the first road over the mountains George William Evans (1775-1852), the assistant surveyor-general, pushed into the grassy plains beyond, becoming the first European to actually cross the Great Dividing Range, and discovered the Macquarie and Lachlan Rivers.

John Oxley (1785?-1828), the surveyor-general, was impressed by his deputy's discoveries and in 1817, with Evans as second-in-command, he led an expedition along the Lachlan River until their way was blocked by impassable marshes. A year later, again accompanied by Evans, Oxley traced the course of the Macquarie River hoping it would lead to an inland sea. He discovered the Castlereagh River before turning north-east and east across the Warrumbungle Ranges and the fertile Liverpool Plains to the Hastings River which he followed to the coast at Port Macquarie.

• See works and highlights from the Surveyor's notebooks

In 1828, Charles Sturt (1795-1869) set out to find the source of the Macquarie River and in the process discovered the Bogan and Darling Rivers. In the following year he turned his attention to the Murrumbidgee River which he navigated in a whaleboat to its junction with the Murray. After turning into this 'broad and noble river' he came across another river flowing in from the north which he correctly identified as the Darling. He continued his remarkable voyage to Lake Alexandria before turning back.

Thomas Mitchell (1792-1855) succeeded Oxley as Surveyor-General. Between 1831 and 1836. Mitchell made three important expeditions into the interior. In 1831 he led an expedition in search of a large river that had been reported in the north-west. After crossing the Namoi River he reached the Gwydir River and turning north discovered the McIntyre River. Four years later he journeyed down the Bogan and Darling Rivers until the hostility of the Aboriginal people forced him to return home. In 1836 Mitchell set out on his third and most successful expedition. After following the course of the Lachlan to the Murrumbidgee he marched across country to the Murray. Then striking south he encountered a rich and verdant region he called 'Australia Felix' (now Victoria).

In 1844 Sturt led another expedition to find the inland sea. This time he intended to journey into the centre of Australia. After travelling through extremely difficult country and enduring scorching heat he reached the waterless Simpson Desert. Reluctantly, Sturt was forced to realise that there was no inland sea.