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.
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.
Pink Lake, also known as, Spencer Lake hasn't been pink for over 10 years.
More information you will find here: https://en.wikipedia.org/wiki/Pink_Lake_(Western_Australia)