Charles Ellicott Commentary Exodus 14:22

"And the children of Israel went into the midst of the sea upon the dry ground: and the waters were a wall unto them on their right hand, and on their left." — Exodus 14:22 (ASV)

The waters were a wall to them. —Any protection in Scripture is called “a wall” or “a rampart” (1 Samuel 25:16; Proverbs 18:11; Isaiah 26:1; Jeremiah 1:18; Nahum 3:8).

In the present case, the waters protected Israel on either flank—the Red Sea on the right, the Bitter Lakes on the left. Poetical writers, as was natural, used language still more highly metaphorical (Psalms 78:13; Exodus 15:8) and spoke of the waters as standing on an heap.

Hence, some moderns have gone so far as to maintain that on this occasion the water “gave up its nature, formed with its waves a strong wall, and instead of streaming like a fluid, congealed into a hard substance” (Kalisch). But this is to turn poetry into prose and enslave oneself to a narrow literalism.