There’s no rest for the wildebeest, especially as it crosses the crocodile-infested Mara River between Kenya and Tanzania, shown here. Each year, as many as 1.5 million blue wildebeest move through this region following seasonal rains. The annual migration is one of the world’s great wildlife spectacles, a journey that will take the wildebeest some 800 miles, as they seek out lush, green grass and fresh water. August often finds the herd here in the northern Serengeti Plains, a favorite destination for safari-goers who will also see some 200,000 zebras—as well as smaller numbers of gazelles and elands—that accompany the herd. The great number of animals makes this phenomenon one of the largest land migrations on Earth, often called the ‘world cup of wildlife.’