South Australia.

The Onkaparinga River is the second largest river in South Australia, it winds its way through the ranges, empties into the Clarendon weir before continuing through the Onkaparinga Gorge to Old Noarlunga.
At Old Noarlunga the river briefly enters the plains before flowing through the estuary and out into the ocean.
The Onkaparinga River National Park, which encompasses an area from where the river enters a steep sided valley and flows into a gorge with cliffs up to 50 metres high and large permanent rock pools