Imagine squinting into the shimmering Serengeti horizon and seeing a herd of wildebeest trundle into view. They’re moving slowly, stopping every now and then to graze on what’s left of the parched savannah. At first, they number a couple of dozen, but as you watch, tens become hundreds, and hundreds become thousands. And still they come – a snorting, braying mass, relentlessly marching north in search of food. This is the wildebeest migration, and watching it play out on the sweeping plains of Tanzania’s Serengeti National Park is unforgettable.

The statistics are staggering: in May each year, over 2.5 million animals, mostly wildebeest but also several hundred thousand zebras and antelopes, set out on a three-month journey from the short-grass plains of the southern Serengeti to Kenya’s Masai Mara Game Reserve. On the way, they’ll cover some 800km of open plains and croc-infested rivers, running the gauntlet of predators such as lions, cheetahs, hyenas and hunting dogs.

By June, the herds have passed deep into the park’s Western Corridor and are nervously starting to cross the Grumeti River. This is the migration at its most savage – and the defining moment of countless wildlife documentaries – as the reluctant wildebeest gather at the riverbank, too scared to go any further, until the mass behind them is so intense that they spill down into the water and are suddenly swimming, scraping and fighting in a desperate attempt to get across. Many are injured or drowned in the mayhem, while huge Nile crocodiles pick off the weak and unwary.

Those that do make it are still some 65km from the Mara River, the last and brutal barrier between them and the rain-ripened grasses of the Masai Mara. Once there, they’ll have three months to eat their fill before going through it all over again on the return journey south.

The best time to see the migration in the Serengeti is between December and July; for the river crossings, visit in June (Grumeti) and July or August (Mara). Check out for up-to-date reports on the location of the herds.