Lake MacDonnell, western Eyre Peninsula, Australia

Lake MacDonnell is a salt lake on western Eyre Peninsula near the Nullarbor Plain. Situated 15 km south of Penong on the way to Point Sinclair. It is the site of a former salt mine and the largest gypsum mine in Australia, on the largest gypsum deposit in the southern hemisphere. The ore body consists of calcrete coastal dunes of the Pleistocene Bridgewater Formation in a 20-kilometre (12 mi) northwest-trending depression. The gypsum formed during the Holocene period. The gypsum deposit has a one-metre layer of gypsarenite containing 93 percent gypsum calcium sulphate. Below that is a 5-metre (16 ft) layer of selenite containing 94-96% calcium sulphate.

High in salt concentration, the lake gives the impression of a salmon pink lake on clear days. One side of the causeway is Pink Lake, the other side is Green Lake and further down over the small bridge is the Blue Lake. The Pink Lake is caused by salt loving algae called dunaliella salina and bacteria called halobacteria that secrete carotenoid red pigments, that turns the water bright pink.

This area is also known as the Nullabor. When people refer to the Nullabor they generally mean the huge area of deserted land. The striking pink waterscape separated from a neighbouring blue-green lake by a gunbarrel-straight dirt road is Lake MacDonnell, near Penong by the Nullarbor Plain.

The best time to visit lake Macdonnell on the Eyre Peninsula depends on your plans before and after you visit. Usually, the only people who visit Lake Macdonnell are the people crossing the Nullabor, due to its remote location, or locals who know that Cactus Beach is a great surfing spot.