betweenjune to september each year over 1.5 million wildebeest make the 300—mile round trip from the serengeti in tanzania to the maasai mara here in kenya in search of fresh grass. that's if they can get past the lions, the hyenas and cheetahs laying in wait for them. they then have to tackle the steep—sided rivers that cross the migration route. most of these rivers are teaming with nile crocodiles that can grow up to 20 feet in length. the river crossings are pure natural theatre, and they're