The Sahara, the largest tropical desert in the world, is called by the Bedouins “Bar Bela Mar” which means a sea without water, which the waves and deceiving dunes made by the sand make almost ‘navigable’. But deep in the ground, under the dunes and stone heaps, lies an enormous supply of water, a giant system of reservoirs with groundwater over three thousand years old. This treasure supplies the oases and artisan wells some of which, for example at Gadames, have permitted permanent settlements for more than ten centuries. Many oases however appear and disappear for no apparent reason. According to President Gaddafi’s revolutionary programmes, the groundwater should be brought to the surface by a pumping system and then sent through huge cement pipes to the Mediterranean coast 5000 kilometres away. It is not known, however, if this plan, which has already scattered 64 billion dollars in the sand, will work in the end and if the underground reserves will be able to supply a flow of 70,000 litres per second for a long time. The Austrian, Michael Schlamberger, who has made several appreciable films on various aspects of nature, explores with his team a completely arid world which he is not used to and which reserves many surprises.