What is the name of the famous pink lake in Western Australia?

The famous pink lake in Western Australia is Lake Hillier.

Lake Hillier is a saline lake on Middle Island in the Recherche Archipelago, off Western Australia's southern coast near Esperance. Its striking pink colour contrasts sharply with the dark blue ocean beyond the island's narrow coastal strip, making it one of Australia's most recognizable natural curiosities.

The lake is approximately 600 metres long and 250 metres wide. Its colour has been linked to salt-loving microorganisms, especially the algae Dunaliella salina, along with halophilic bacteria and archaea that produce red or orange pigments in highly saline conditions. The exact appearance can vary with rainfall, evaporation and salt concentration; recent observations have reported that the colour has faded at times after heavy rain.

Lake Hillier is often confused with Pink Lake near Esperance, which historically appeared pink but has not consistently shown that colour in recent years. Lake Hillier was recorded in the journal of explorer Matthew Flinders after his visit to Middle Island in January 1802. It is protected within the Recherche Archipelago Nature Reserve.