The lakes on the world’s biggest sand island, K'gari, are famous. Pivotal to the World Heritage listing of the Queensland island formerly known as Fraser Island, their turquoise waters feature in international tourism campaigns and social media posts.

K'gari has more than 40 unique lakes, some more than 55,000 years old. They range from the photogenic clear waters of Boorangoora (Lake McKenzie), pictured above, which filters through the sand dune it rests in, to the emerald-green waters of Lake Wabby, a window lake which is (very) slowly being swallowed by a giant sand dune.

In fact, K'gari is home to more than half of the world’s perched lakes, more than 50, including Boorangoora. Perched lakes form when sand is cemented together with decomposed organic matter (such as leaves and bark), aluminium and iron. This creates an impermeable layer well above sea level. It’s remarkable these lakes exist, given water usually passes quickly through sand.

Until now, it was believed K'gari’s lakes would have contained water since the last ice age ended, about 11,500 years ago. But our new research found some of the island’s deepest lakes dried out only 7,500 years........

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