Again on the 24th of December, the Mermaid left Port Jackson on a short trip to Tasmania, from which they returned in February, 1819.

Once more the busy little Mermaid sailed from Sydney on the 8th of May, 1819, to make a running survey of the east coast.

On this voyage, many ports hitherto unvisited were examined by King, and amongst other places, Cunningham paid his first visit to the Endeavour River.
Continuing the survey, she rounded Cape York, crossed the mouth of the Carpentaria Gulf, and kept along the north coast, where King found Cambridge Gulf.

At Cassini Island, the Mermaid left for Timor, and eventually returned to Sydney round the west coast of Australia.
*[Footnote.] For the accompanying notes of Allan Cunningham's earlier lifework I am indebted to the Biographical Notes concerning Allan Cunningham, compiled by Mr.J.H.Maiden, Director of the Sydney Botanical Gardens.
On the 14th of June, 1820, the Mermaid was again busy with King and Cunningham on board, and, sailing up the east coast she re-visited the Endeavour River.

During their stay, Cunningham ascended Mount Cook, where he made a fine collection of seeds and plants.