Tarangire National Park is the sixth largest national park in Tanzania. The name of the park originates from the Tarangire River that crosses the park. The Tarangire River is the primary source of fresh water for wild animals in the Tarangire Ecosystem during the annual dry season. The Tarangire Ecosystem is defined by the long-distance migration of wildebeest and zebras. During the dry season thousands of animals concentrate in Tarangire National Park from the surrounding wet-season dispersal and calving areas.