The Okavango Delta (or Okavango Swamp), in Botswana, is a large 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 kilometres of water spread over the 6,000-15,000 km² area. Some flood-waters drain into Lake Ngami. The Moremi Game Reserve, a National Park, spreads across the eastern side of the Delta.
The area was once part of Lake Makgadikgadi, an ancient lake that mostly dried up by the early Holocene. Although the Okavango Delta is widely believed to be the world's largest inland delta, it is, in fact not. In Africa alone there are two larger similar geological features - the Sudd on the Nile in South Sudan, and the Inner Niger Delta in Mali.