The Serengeti is a plain that runs to the horizon in every direction, and the stage for the largest land-animal migration on Earth. Its name is the Maasai word siringet, for land that seems to run on without end. Across roughly 15,000 square kilometres of northern Tanzania, the ground really does dissolve into grass and sky. That expanse is the core of a 30,000-square-kilometre ecosystem shared with Kenya's Maasai Mara. Close to two million wildebeest, zebra and gazelle move through it on a yearly circuit, and the hunters move with them. This is some of the densest big-cat country in the world, holding one of Africa's largest lion populations. Flat-topped acacias stand alone in the grass, and ancient granite outcrops called kopjes break the flatness, each one an island of shade a lion or a leopard can climb to watch the plain. Tanzania made it the country's first national park in 1951.
You feel the scale at dawn, when mist still hangs over the grass and a pride lies in the acacia shade, digesting the night. In calving season the plains become a nursery: newborn calves stagger upright within minutes, while cheetahs and hyenas work the edges of the herds. By the dry months the herds have moved north, and at the river crossings there they brave the same crocodile-lined banks that Kenya's reserve is famous for. More than any single view, that unbroken circuit is the real spectacle, and no one visit ever catches all of it. At first light you can drift over the whole plain in a hot-air balloon, the herds spreading dark across the grass below.