Once one wildebeest is brave enough to cross the river, everyone else follows and it is chaos. They will run, jump, fall or slide off of the cliff to get to the water and nothing will stop them (except maybe a crocodile). It is thrilling to watch but the whole event only lasts a few minutes.
Maralee
Through My Lens 
Quite a spectacular event.
It really is.
Were there any places where the banks had gentler slopes?
I mean, it’s a long river; that doesn’t seem like the optimal place to cross.
It’s pretty steep all along the river and from what I observed the gentler slopes areas were full of crocodiles
That makes sense.
. . . plus, I get to make puns . . . gnus travels fast. Flying gnus. Gnus banks.
. . . I could go on . . .