Imagine crossing the grassy plains of northern Serengeti with your guide, and coming across millions of wildebeests and zebras, moaning and bleating as they attempt to cross a river full of crocodiles. This is the famous Mara River crossing of the Great Migration, a natural wonder that every year between July and October can be witnessed in the northern part of Serengeti National Park. This will be a nerve-racking event to watch – for did we mention the big cats waiting on the other side, just as hungry for meat as the herds are for greener pastures…?