More than 1 million wildebeests, half a million gazelles, and 200,000 zebras constantly on the move -- they're all in search of fresh grass and water.
Welcome to the Serengeti and the Masai Mara plains in the heart of East Africa -- the seventh New Wonder of the World.
Covering about 10,000 square miles of land teeming with life, the Serengeti is home not only to some of the most diverse wildlife on this planet, but the start and finish line for one of the world's last great migrations.
"Good Morning America's" expert panel had a spirited debate about the merits of a moveable, natural wonder of the world.
"It's one of the great wonders in terms of animal migrations," said oceanographer and panelist Sylvia Earle. "It's just over the top."
In the end, the uniqueness of the area and the preservation it provides to so many species living in harmony landed it on our list.
"Serengeti-Mara ecosystems [are] considered to be perhaps the last of the ecosystems … in which … human impact is less than 5 percent," said professor Karim Hirji, former director of the Serengeti Wildlife Research Center.
Year-round, wildebeests, zebras and gazelles roam, pushing ever forward in a clockwise rotation covering the Serengeti in Tanzania and Masai Mara in Kenya, along the way encountering friends and foes alike.
"There's high drama almost the whole time," said tour guide David Bromham. "If they're not birthing 300,000 calves in the 3½-week period, they're leaping into rivers for 20 [feet] up."
Wildebeests may have been making the trek for millions of years, coping with disease, drought and predators.
"It would be astonishing and wondrous to watch the migrations go by," said Neil deGrasse Tyson, a panelist and astrophysicist.
Those lucky enough to travel here see wild animals in their purest state.
On the East African plains, you'll see lions, elephants, giraffes, and lots of wildebeests.
Guide Gerald Selempo told "Good Morning America's Weekend Edition" anchor Kate Snow that the locals had a nickname for them.
"They call them 'the clowns,' because when you look at a wildebeest he looks like he was made up of the leftovers of all the other animals," Selempo said. "They have like a head of a buffalo, have tail of a horse. They have legs of an antelope. They just don't look very balanced."
But the wildebeests do bring balance to this fragile ecosystem, made up of the Serengeti and the Masai Mara. They are the heart and soul of the Great Migration -- the key to survival on the vast plains.
"Without the migration, it's harder to conceive Serengeti-Mara being what it is today," Hirji said. "Everything else survives within that migration -- the predators and so on the vegetation."
The journey is quite literally the circle of life. It happens year-round, a 700-mile trek, finely tuned to the region's rainy seasons. The herds follow the rain.
"They just move and hopefully wherever they are going they can get as much grass and as much water as possible," Selempo said.
After spending the late summer and early fall in the north, here in the Masai Mara, dry land and lack of food forces the herds south to the Serengeti, which is lush with new grass.
There's even a pattern to the way they eat. First, the zebras come.
"The zebra seems to be eating the top grass," Selempo said. "The wildebeests go for the middle and then the herd beasts. … Like the gazelles, go for the lowest part."