Like an African safari in miniature, the Ngorongoro Crater is an iconic soup bowl filled with animals and wrapped in superlatives. As the largest un-filled, unbroken caldera in the world, the crater boasts a number of 'records', including the densest animal population in Africa. No wonder it is dubbed as the 8th Wonder of the World. Created some three million years ago when a large volcano exploded, the caldera is ca 20 km across and 610 metres deep; and contains all the 'Big Five' as well as a number of other plains game. Only the giraffe is absent, as the caldera walls are too steep for them to climb.