Lake Hillier is a pink-colored lake on Middle Island, the largest of the islands and islets that make up the Recherche Archipelago, Western Australia. From above the lake appears a solid bubble gum pink. It is such a significant distinguishing feature of the archipelago that air passengers often crane their necks to take a glimpse of it.
The lake is about 600 meters long, and is surrounded by a rim of sand and a dense woodland of paperbark and eucalyptus trees. A narrow strip of sand dunes covered by vegetation separates it to the north from the Southern Ocean.