The Ngoron­goro is a col­lapsed crater on the edge of the Serengeti. It was formed when a huge vol­canic moun­tain sud­den­ly crashed into itself at this spot. The crater bot­tom is at approx­i­mate­ly a height of 1700 metres and the side walls are between 400 and 600 metres high, so that the crater edge is at approx­i­mate­ly about 2300 metres. The diam­e­ter of the crater is between 17 and 21 kilo­me­tres. The crater has a total area of 26,400 hectares. About 25,000 large mam­mals pop­u­late the crater, with the high­est preda­tor den­si­ty in Africa among them.