In 1836 William Light arrived ahead of the settlers and examined the coast of South Australia, in particular looking for a fine harbour described by Captain Jones, a sealer. On September 28 Light returned to an earlier anchorage and William Field and William Pullen each explored again the inlet they had examined on the 26th. Their descriptions of the inlet were very different from Captain Jones's, with two channels and two islands, and no fresh water. This was the Port River Inlet and was considered a good site for a harbour.

  

During the course of this search, the Onkaparinga River was again found. In his Brief journal Light records that on the 3 October a large river was sighted but it was not until the 10 October that they located it and William Pullen was sent to examine it.  He reported that he had been unable to enter the river because of the large surf at the mouth.  He was however able to see some distance upstream and described it as a large river. The river is not named on Light's chart of the east coast of Saint Vincent's Gulf but its mouth is marked as 'Oct 10'.  In his surveys to find the best site for the capital of the new province of South Australia Light examined Kangaroo Island, Port Lincoln, and Encounter Bay. 

Having found the site for a harbour, and explored the eastern side of St Vincent's Gulf, Light's attention was turned inwards to the land.