The Ngorongoro Crater in northern Tanzania, in the southeastern of Serengeti National Park, is one of the best-preserved calderas in the world. It measures a vast 12.4 miles across, with walls reaching up to a third of a mile high. Across the savanna that covers the crater floor, wildlife thrives. You’ll cross paths with herds of antelopes, giraffes, zebras, and hippos. If you get lucky, you may even spot lions hunting prey. Hiking trails dot the crater and vary in difficulty. Your local agent can recommend the best for your experience level.