4. Ngorongoro Crater, Tanzania
The Ngorongoro Crater is a unique UNESCO World Heritage Site and the largest unspoiled, dry volcanic caldera in the world. It formed when a large volcano exploded and collapsed on itself 2 to 3 million years ago. The crater stretches 19 km across and is 600 meters deep. The Ngorongoro Crater forms the Ngorongoro Conservation Area and acts as a protective enclosure for more than 25,000 large animals, such as hippopotamus, black rhinoceros, zebra, wildebeest, gazelles, lions and eland.