Lake Hillier, Middle Island, the largest of the islands and islets that make up the Recherche Archipelago, Western Australia.
The most most notable feature of the lake is its pink colour. It’s such a significant distinguishing feature of the archipelago that air passengers often take note of it. The pink colour is permanent, and does not alter when the water is taken in a container. Although the source of the pink colour has not been definitively proven in the case of Lake Hillier, the pink colour of other salt lakes in the region arises from dye created by the organisms Dunaliella Salina and Halobacteria. Another hypothesis is that the pink colour is due to red halophilic bacteria in the salt crusts.
The lake is 600m (1,969 ft) long and 250m (820 ft) wide.