Legends about the dune's origins are abundant - some claim the great Mongol conqueror Genghis Khan was buried beneath it
Rising incongruously above the steppes of southeastern Kazakhstan is a structure as famed for the myths that surround as for the sound it produces - a single, singing dune.
Located between the folds of the Tian Shan mountains near the Chinese border, the 150-metre-high by three-kilometre-long dune generates a low-pitched, organ-like rumble in dry weather.
Before physicists established that the sound came from sand grains rubbing against each other, legends about its origins abounded, some claiming the great Mongol conqueror Genghis Khan was buried beneath it.
The sand hill is one of the main attractions of the Altynemel national park some 180 kilometres (110 miles) northeast of Kazakhstan's commercial hub Almaty.
The park also features volcanic mountains, millennia-old burial sites of the rulers of the Saka, an ancient nomadic tribe, and numerous wild animals including goitered gazelles known for their lightning-fast, bounding gait.
Altynemel is adjacent to another national park, Charyn, set up around a 154-kilometre-long canyon that travellers do not notice until they are nearly on top of it.
The part frequented by tourists is called the Valley of Castles, where some rocks are shaped like the towers of a mediaeval fortress.