The Sahara is the world’s largest hot desert and second largest desert, after Antarctica. At over 9.4 million square kilometres (3.6 million square miles), it covers most of Northern Africa, making it almost as large as China or the United States. The Sahara stretches from the Red Sea, including parts of the Mediterranean coasts, to the outskirts of the Atlantic Ocean. To the south, it is delimited by the Sahel, a belt of semi-arid tropical savanna that composes the northern region of central and western Sub-Saharan Africa.
Some of the sand dunes can reach 180 metres (590 ft) in height
Most of the Sahara consists of rocky hamada and ergs (large areas covered with sand dunes) form only a minor part.
Erg Chebbi is one of Morocco’s two Saharan ergs and the dunes of Erg Chebbi reach a height of up to 150 metres and cover an area of 22 kilometers from north to south and up to 10 kilometers from east to west.