The Okavango Delta (or Okavango Grassland) (formerly spelled Okovango or Okovanggo) in Botswana is a very large, swampy inland delta formed where the Okavango River reaches a tectonic trough in the central part of the endorheic basin of the Kalahari. All the water reaching the Delta is ultimately evaporated and transpired, and does not flow into any sea or ocean. Each year approximately 11 cubic kilometers of water spreads over the 6,000-15,000 km2 area. Some flood-waters drain into Lake Ngami. The Moremi Game Reserve, a National Park, is on the eastern side of the Delta. The scale and magnificence of the Okavango Delta helped it secure a position as one of the Seven Natural Wonders of Africa, which were officially declared on February 11, 2013 in Arusha, Tanzania. On 22 June 2014, the Okavango Delta became the 1000th site to be officially inscribed on the UNESCO World Heritage List.