People have lived on parts of the Karas coastline for a very long time, with archaeological remains near the Orange River mouth dating from about 800,000 years ago. While conditions along the Orange have probably been conducive to human habitation for much of the time because of the availability of fresh water, early inhabitants were also attracted to rich supplies of food from the sea. These early inhabitants are likely to have been nomadic along the very arid coastline moving from one water source or good hunting area to another. The limited supply of water for both people and livestock made much of the coast inhospitable, leaving the environment largely unspoilt. After the discovery of diamonds near Lüderitz in 1908 a huge area was declared off-limits to protect diamond mining interests. This designation excluded all non-mining access and ensured that much of Karas' coastal area remained pristine. Coastlines are the narrow interface between the Earth's three great realms – the land, the atmosphere and the oceans. This is the zone where a diversity of life is often concentrated, with some species from the sea, others from the land, and those that occur only in the thin inter-tidal strip itself. Processes operating in one domain affect the other. For example, the cool ocean moderates temperatures on land, while the land provides nutrients to the oceans. Conditions along coasts are also influenced by tidal changes and particularly by weather, such as wind and the waves and currents driven by atmospheric circulation. The Karas coast is characterised by extreme aridity, frequent fog and almost constant southerly winds. Offshore, the cold Benguela Current and its associated upwelling cells are rich in nutrients. Most of the coastline consists of rocky stretches interspersed with sandy beaches and bays, and with salt pans and gravel plains inshore. The Karas coast includes a number of areas which are internationally recognised for the diversity of life they support. Falling within the transition area between winter and summer rainfall, the Sperrgebiet National Park incorporates 80% of the Succulent Karoo Biome, an area recognised by botanists as one of only 34 biodiversity hotspots on earth. It is an area of tremendous plant diversity, of which many are succulents that have restricted ranges or are endemic species (species which occur nowhere else). The Orange River mouth is recognised as an internationally important wetland, and the islands hold globally significant seabird populations. The northern section of the Karas coastal region falls within the Namib Naukluft Park.