Tallest sand dunes (free-standing)

The free-standing megadunes in the Badain Jaran Desert in the Inner Mongolia region of northern China have an average height of 330 metres (1,082 feet), but have measured as much as 460–480 metres (1,509–1,574 feet) high – which is taller than New York's Empire State Building. Scientists suggest that geology of the bedrock below the dunes as well as high water content in the sand which means that grains "stick" together are two of the factors that explain their extreme height.

Badain Jaran covers an area of approximately 49,000 square kilometres (18,900 square miles).

In addition to its superlative sand dunes, it is also famous for the 100 or so lakes that sit among the megadunes – most of which are thought to be fed by underground springs. In fact, the name "Badain Jaran" comes from the Mongolian for "mysterious lakes".

Other taller dunes are reported, such as Duna Federico Kirbus in Argentina, but these may be "sand ramps" or "climbing dunes" rather than free-standing dunes – sand banked up over pre-existing features such as mountains.