The Aussies tell us:
Lake Hillier is a pink-coloured lake on Middle Island, the largest of the islands that make up the Recherche Archipelago off the coast of Esperance.
From above the lake appears a solid bubble gum pink. The lake is about 600 meters long, and is surrounded by a rim of sand and dense woodland of paperbark and eucalyptus trees. A narrow strip of sand dunes covered by vegetation separates it from the blue Southern Ocean.
No-one fully knows why the lake is pink. Scientists speculate that the colour comes from a dye created by bacteria that lives in the salt crusts.I ragged on Australia in the previous post, so consider this a make-good. Besides, it's interesting.