Exodus 15:10

Thou didst blow. This statement presents another fact not mentioned in the direct narrative of the destruction of the Egyptians, though it is in complete harmony with it. As a strong east wind had separated the waters and held them back for the Israelites, now a wind from the west or northwest brought the waters back upon the Egyptians. In obedience to its Creator, wind effectively served to rescue one people and to destroy another.

Sank as lead. The first stanza ended (v. 5) by comparing the drowning Egyptians with sinking stones. The second stanza ends with a similar expression, comparing the Egyptians to lead. The waters into which they sank are called “mighty” because of the mighty proof of the Creator’s glory provided by the waves rushing majestically back to fill their usual space. Here Miriam’s chorus (v. 21) probably interposed again.