Wildlife expert Yu Yat-tung and nature lover Andrew Leung Yiu-kai have visited the animal paradise in the past few years to marvel at the thundery progression that is filled with drama and danger.
Grazing animals are in tune with the seasons. They go where the rain falls, always seeking drinking water and greener pastures. In spring, they breed and rear their young in Tanzania's Serengeti region. When the seasonal drought in June dries up their grass, they move on to the lush plains of Kenya's Masai Mara. Once resources there are exhausted in November, they make their way back.
Their annual pilgrimage follows more or less the same schedule and route.
Every year, 1.5 million wildebeest - Dutch for wild beast - travel about 3,200km, equivalent to running 76 full marathons. The sheer number of animals left Leung stunned as he watched from a hot air balloon last August.
"The wildebeest look like an unending brown band on the golden plains," Leung says. "Several million hooves kick up clouds of dust on the way."
For Yu, it was breathtaking to see the action live - and up close - after having seen many documentaries about the migration on television.
"When I was there last year, thousands of wildebeest blocked the road we were driving on," Yu recalls. "We had to wait ... Roads and grassland make no difference [to them]."
Animals choose the shortest route - straight lines - to their destination, whether the obstacles are hills or predator-filled rivers.
Wildebeest usually take the lead, while the zebra and gazelle trail behind. Even calves as young as six months need to embark on the trek.
As they go, they attract lions, leopards, hyenas and wild dogs. The predators hang about, waiting to pounce on the weak, young or those animals that wander too far from the herd.
"It is easy to see a kill in action. A friend on my trip saw a cheetah use our jeep as a shield while it spied on prey," Yu recalls. "Then it darted forward and caught an antelope."
Yu says the dramatic climax of the trek occurs at the final challenge - the Grumeti River.
Some of the animals tread safely through shallow waters, while others unknowingly forge into deeper and fast-flowing sections where they drown, or get ambushed by enormous Nile crocodiles.
"I saw carcasses piled up along the river bank while scavengers like vultures and marabou stork took advantage," Leung says. "Their journey is not made without sacrifice."
Fortunately, there is safety in numbers. The predators can take only one prey at a time, so the rest that survive the crossing are home free.
Seventy-five per cent of the wildebeest make it to safe grounds.
"It seems they are following nature's command," Leung says. "They risk their lives confronting the obvious threats to reach their destination.
"They have a greater mission, a greater vision - it really holds me in awe."
Wildebeest grazing on the African plains