Lake Hillier is a pink-coloured lake on Middle Island in Western Australia. Middle island is the largest of the islands and islets that make up the Recherche Archipelago, a group of about 105 islands and over 1,200 ‘obstacles to shipping’.
The tiny lake only spans about 600 meters wide but its rose pink colour in unmistakable. However, the reason why it’s pink remains a mystery.
The shallow briny lake is rimmed with white salt and encircled by dark green forests of eucalyptus and paperbark trees. A narrow strip of white dunes and sand separates the lake from the ocean’s deep waters. The first reported sighting dates back to the journals of Matthew Flinders, a British navigator and hydrographer in 1802. Flinders had climbed Middle Island’s highest peak (now known as Flinders Peak) to survey the surrounding waters when he came across this remarkable pink lake.
The reason for the lake’s colour is still under investigation. A possible explanation according to some scientists involves the low nutrient concentrations and different types of bacteria and algae. The pink colouration could also be from a sea salt and nahcolite (sodium bicarbonate) deposit reaction or red halophilic bacteria in the salt crusts.
