The Hillier Lake is a salt lake in the Western Australia. The lake is notable for its high salt content and its pink hue.
From above the lake appears a solid bubble gum pink. The lake is about 600 meters long, and is surrounded by a rim of sand and dense woodland of paperbark and eucalyptus trees. A narrow strip of sand dunes covered by vegetation separates it from the blue Southern Ocean.
The distinctive colour of the water is due to the presence of the green alga Dunaliella salina, halobacterium Halobacteria cutirubrum, and/or high concentration of brine prawn.
The lake is not always pink. With salinity level greater than that of sea water, temperature high enough and adequate light conditions, the alga begins to accumulate the red pigment beta-carotene, the pigment responsible for the hue. The pink halobacterium grow in the salt crust at the bottom of lending it its unusual colour.