Coorong

"The Coorong, a narrow neck of sand dunes stretching 145 km along the south-east coast of South Australia [...] is now a 46,745 hectare National Park. The word 'coorong' is generally accepted to be a corruption of the local Aboriginal word 'kurangh' meaning 'neck'.

Geologically The Coorong is a set of complex and ancient sand dunes. The oldest was probably formed about 120,000 years ago. Then there is another dune formation which is about 80,000 years old. Some of that dune still remains on Younghusband Peninsula. The modern day Coorong was formed between 6,000 and 20,000 years ago when the sea rose to form an island on top of the 80,000 year old dune. This produced a lagoon behind the present line of seaward dunes. At the time there were probably many access points from the sea to the lagoon but over time the wind and the sands filled these in creating this unique neck of land."
www.walkabout.com.au/locations/SACoorongThe.shtml