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The vivid, bubblegum-pink waters of Lake Hillier present a truly mesmerizing spectacle on Middle Island, off the coast of Western Australia. This relatively small saline lake, approximately 600 meters long and 250 meters wide, is dramatically contrasted by the deep blue of the Southern Ocean, from which it is separated by a narrow strip of sandy dunes and lush eucalyptus and paperbark trees. What makes this natural wonder particularly astonishing is that its vibrant hue is permanent, consistently displaying its rosy shade year-round, and remarkably, the water (Review) retains its distinct pink color even when collected in a container.
Scientists have extensively studied Lake Hillier to unravel the mystery behind its peculiar coloration. The primary explanation points to the presence of Dunaliella salina, a unique microalga that thrives in hypersaline environments. Under conditions of high salt concentration, intense sunlight, and elevated temperatures, this alga produces carotenoid pigments, such as beta-carotene, which is also found in carrots. Further research by the Extreme Microbiome Project has also highlighted the significant contribution of halophilic bacteria, like Salinibacter ruber, and archaea found in the lake's salt crusts. These salt-loving microorganisms synthesize their own reddish pigments, like bacterioruberin, which collectively enhance the lake's brilliant pink appearance.
The lake's extreme salinity, comparable to that of the Dead Sea and roughly ten times saltier than the ocean, creates an environment where these specialized microorganisms can flourish. Discovered by British navigator Matthew Flinders in 1802, who noted its rose color and high salt content, Lake Hillier has a brief history of salt mining in the late 19th and early 20th centuries. Today, it stands as a protected nature reserve, and while swimming is considered safe, access is restricted, making aerial views the most common way to appreciate its breathtaking, unearthly beauty.