Lake Hillier is a lake on Middle Island, the largest of the islands and islets that make up the Recherche Archipelago, Western Australia.

 

The most notable feature of the lake is its pink color!

 

It is such a significant distinguishing feature of the archipelago that air passengers often take note of it. The color is permanent, and does not alter when the water is taken in a container.

 

Although the source of the pink color has not been definitively proven in the case of Lake Hillier, the pink color of other salt lakes (e.g., Pink Lake) in the region arises from a dye created by the organisms Dunaliella salina and Halobacteria. Another hypothesis is that the pink color is due to red halophilic bacteria in the salt crusts. Despite the unusual hue, the lake exhibits no known adverse effects upon humans. From above, the lake appears a solid bubble gum pink, but from the shoreline it appears more of a clear pink hue. The shoreline is also covered in salt crust deposits.