The Great Migration is quite simply the greatest gathering of terrestrial megafauna in the world today. In a given day you can see hundreds of thousands of wildebeest not to mention the zebra and other grazers. And the vast majority will successfully cross, perhaps several times, the Mara River aka the herbivore River Styx.

Like all good adventures, it starts out with hope and the promise of literal greener pastures. The herbivores set out from the Serengeti to feast on the long fresh grasses of the Masai Mara.

Nothing is more terrifying to wildebeest than crossing a river. This is a place of death for them and it creates palpable fear and panic in the herd.

River crossings for wildebeest is an event to be feared. The rivers are filled with massive flesh-hungry crocodiles, not to mention aggressive hippos, that sit around for long stretches of time just waiting for meat-on-the-hoof to cross. For the wildebeests, this threat causes them to panic while crossing.

It is a hurried entrance in the river and an even more urgent exit. If the wildebeest are lucky they will survive the crocodile gauntlet and the river current. All they need to do now is safely exit the river.

A photograph makes the river crossing look placid, but it is anything but. The rocks are slick and the wildebeest push each other in a panic to exit the river. This is the time of their greatest danger.

However, wet rocks make for an unlikely adversary for the panicked wildebeest. For some, it’s all too easy for a panicked step to cause a hoof to slip off of the wet rocks. An injured hoof or torn muscle means that wildebeest will never get off of the river’s edge.

Poor chap wrecked his leg in a panicked attempt to get out of the river. As he couldn’t hoist himself out of the river it was only a matter of time before his head slipped under the water to come out no more.

And wildebeest by the dozen injure themselves on those wet rocks. None of the injured make it out alive. The River Styx swells with the dead.

At any given spot on the Mara there are several to dozens of dead wildebeest. Death on the river is inescapable.

And this mass death is glory to the flesh eaters. Crocodiles are so bloated on flesh that they don’t even bother to eat the dozens of additional carcasses around them.

This crocodile, along with several of its friends, were so filled with flesh that they completely ignored the bodies strewn about the river.

Vultures follow the crossings and feed on the dead on the river banks and those that are partly submerged.

Vultures don’t have to compete with each other for a carcass. There is plenty to go around for all.

For those that survive the crossings, they get the opportunity to eat, breed, and cross again. For the rest, there will be no greener pastures. They belong to the River Styx now.