Charles Ellicott Commentary Exodus 14:21

"And Moses stretched out his hand over the sea; and Jehovah caused the sea to go [back] by a strong east wind all the night, and made the sea dry land, and the waters were divided." — Exodus 14:21 (ASV)

The Lord caused the sea to go back by a strong east wind. —By “a strong east wind” we are at liberty to understand one blowing from any point between N.E. and S.E. If we imagine the Bitter Lakes joined to the Red Sea by a narrow and shallow channel, and a south-east wind blowing strongly up this channel, we can easily conceive that the water in the Bitter Lakes might be driven northward and held there, while the natural action of the ebb tide withdrew the Red Sea water to the southward. A portion of the channel might in this way have been left dry and remained so until the wind changed and the tide began to flow.

It is true that Scripture does not speak of the ebb and flow of the tide, since in them there was nothing unusual; but an Egyptian tradition distinctly stated that “Moses waited for the ebb tide in order to lead the Israelites across” (Artipanus, in Eusebius, Praeparatio Evangelica, 9.27). Whether the whole effect was purely natural, or whether (as in so many other cases) God used the force of nature as far as it could go, and further supernaturally increased its force, we are not told, and we may form whatever opinion we please.

The waters were divided. —The waters of the Bitter Lakes were for a time separated completely from those of the Red Sea. By gradual elevation and desiccation the channel over which the Israelites passed has probably now become dry land.