Who is this, etc.? "Once more surprise at the [same] phenomenon recurs, and in a stronger form; a monstrous, devastating river appears to roll itself wildly along, overwhelming all countries: who is it?
It is Egypt, which is now threatening to overrun the earth and to lay everything waste, whose various nationalities are advancing fully equipped" (Ewald). As a flood; rather, as the Nile (y'or, a word of Egyptian affinities, and only once used of another river than the Nile, Daniel 12:5, Daniel 12:6, Daniel 12:7).
The naturalness of the figure in this context needs no exhibiting. It reminds us of Isaiah 8:7, Isaiah 8:8, where the Assyrian army is compared to the Euphrates. Are moved as the rivers; rather, toss themselves as the rivers.
By the "rivers" the prophet means the branches of the Nile, which are described by the same word in Isaiah 19:8; Exodus 7:19.