It rivals the Amazon River. It's the longest river. And its sources, the tributaries of the Nile River, start even south of this picture, and the water flows northward, and eventually its delta reaches the Mediterranean Sea. The delta, which is where a river opens into the sea, is called a delta because, as you can see, these rivers, you can even see it from the satellite pictures right over here, they start branching up a bunch, and you have this upside-down triangular region, which looks a little bit like an upside-down Greek letter delta. So that's why a river delta is called that. And this one just happens to be upside-down. If it was flowing the other way, it would be a right-side-up delta.