The Nxai Pan in Botswana has been formed by a process that may have begun more than five million years ago. At that time, the Okavango river, the Chobe and the upper Zambezi flowed along somewhat different courses to those of today. Travellers are always struck by the immensity of sky and horizon of the Botswana landscape. Nxai Pan itself is an extensive grass plain, part, once again, of the old lake bed, which is more generously covered with acacia trees. In the south of Nxai Pan, Baines’ Baobabs comprise a clump of large baobab trees, rendered immortal in 1862 by painter Thomas Baines, a member of Livingstone’s expedition.