Look at any map and chances are that all the bodies of water have been coloured blue. But if you were to draw Middle Island, part of Australia’s little-known Recherche Archipelago, you’d need a pink crayon (preferably of a bubble-gum hue) to depict its most striking landmark: Lake Hillier. Scientists aren’t entirely sure how the lake got so pink. After all, it stands in contrast to the deep blue waves of the Southern Ocean just metres away. Unlike most coloured lakes, Hillier’s hue is neither a reflection of the lakebed nor influenced by the dye of seasonal bacteria. As such, it retains its unique pink colour even when placed in a bottle. Middle Island is part of a wilderness area that’s off-limits to tourists, but you can still view Lake Hillier on a two-hour helicopter tour from Esperance, Western Australia.