On the 6th of April, 1817, Oxley left Sydney and joined his party at the depot on the 1st of May.
Thence he soon commenced this most momentous journey in Australia's early annals, eager to penetrate into the unknown, and inspired with hopes of solving the mystery of the outlet of this inland river.
Disappointment marks the tone of Oxley's journal from the start; the exceeding flatness of the country, the many ana-branches of the river, the low altitude of its banks, and the absence of any large tributary streams, above all, the dismal impression made by the monotony of the surroundings, seem to have depressed Oxley's spirit.

He appears to have formed the idea that the interior tract he was approaching was nothing more than a dead and stagnant marsh -- a huge dreary swamp, within whose bounds the inland rivers lost their individuality and merged into a lifeless morass.

A more melancholy picture could not be imagined, and with such an awesome thought constantly haunting his mind there is no wonder that he became morbid, and that the dominant tone of his journal, whilst on the Lachlan, is so hopelessly pessimistic.
"These flats," he says, "are certainly not adapted for cattle; the grass is too swampy, and the bushes, swamps, and lagoons are too thickly intermingled with the better portion to render it a safe or desirable grazing country.

The timber is universally bad and small; a few misshapen gum trees on the immediate banks of the river may be considered an exception." The channel of the river now divided, and Oxley followed the channel on the northern side, which they were skirting.

But before they had progressed a mile beyond the point of divergence, they reached the spot where the river overflowed its banks and its course was lost in the marshes.