Imagine – if you will – an area the size of Portugal, largely uninhabited by humans. Its stark, flat, featureless terrain stretches – it would seem – to eternity, meeting and fusing with a milky-blue horizon. This is the Makgadikgadi – an area of 12 000 sq kms, part of the Kalahari Basin, yet unique to it – one of the largest salt pans in the world.