Ngorongoro Crater is actually a caldera formed by a collapsed volcano. The descent to the base of the crater is 600m and the base at its widest point is 23km long. The high rim of the crater prevents the animals from migrating, but due to the abundance of rain and fresh water, the animals don't really need to. The game viewing is fair, animals are less plentiful than in the Serengeti, but the backdrop at the Ngorongoro and the wonderful climate make the game viewing a stunning experience. Click on thumbnails for a better view.
For more on safari residents, you are invited to view my gallery on Safari Animals.