Jamieson, Fausset and Brown on Isaiah 11:15

15. There shall be a second exodus, destined to eclipse even the former one from Egypt in its wonders. So the prophecies elsewhere (Psa 68:22; Ex 14:22; Zec 10:11). The same deliverance furnishes the imagery by which the return from Babylon is described (Is 48:20, 21).

destroy--literally, "devote," or "doom," that is, dry up; for what God dooms, perishes (Psa 106:9 Na 1:4).

tongue--the Bubastic branch of the Nile [Vitringa]; but as the Nile was not the obstruction to the exodus, it is rather the west tongue or Heroöpolite fork of the Red Sea.

with ... mighty wind--such as the "strong east wind" (Ex 14:21), by which God made a way for Israel through the Red Sea. The Hebrew for "mighty" means terrible. Maurer translates, "With the terror of His anger"; that is, His terrible anger.

in the seven streams--rather, "shall smite it (divide it by smiting) into seven (many) streams, so as to be easily crossed" [Lowth]. So Cyrus divided the river Gyndes, which retarded his march against Babylon, into three hundred sixty streams, so that even a woman could cross it [Herodotus, 1.189]. "The river" is the Euphrates, the obstruction to Israel's return "from Assyria" (Is 11:16), a type of all future impediments to the restoration of the Jews.

dry shod--Hebrew, "in shoes." Even in sandals they should be able to pass over the once mighty river without being wet (Re 16:12).