The Ngorongoro Crater can be found about 180 km from Arusha, considered by many travellers to be the largest natural zoo in the world.

It's a 19km wide caldera, a crater left by an erupting volcano, at the bottom of which live up to 30,000 mammals. Here you can find the Big Five - rhino, elephant, leopard, lion and buffalo.

The two-horned rhinoceros has been almost wiped out by poachers, and you'll find only a few of the last of them here. There are three roads leading into the crater and the 600m high wall can be climbed in half an hour by car. One road is two-way, with tourist jeeps usually using one for the descent and the other for the ascent. On the two-way road in the morning you can observe the Maasai descending into the crater with their herds to water the cows.

Humans have not been allowed to live in the crater since 1975, however the Maasai are allowed to stay in the Ngorongoro Conservation Area, an area that extends around the crater. As a result, Maasai bomas, villages where tourists can meet Maasai for a fee, have also sprung up. However, it's all in the form of an open-air museum and the Maasai have become accustomed to the dollar, they are tough traders, nothing but cattle is worth anything to them.