Albert Barnes Commentary Exodus 14:26

"And Jehovah said unto Moses, Stretch out thy hand over the sea, that the waters may come again upon the Egyptians, upon their chariots, and upon their horsemen." — Exodus 14:26 (ASV)

That the waters may come - A sudden cessation of the wind, possibly coinciding with a spring tide (it was full moon), would immediately convert the low, flat sandbanks first into quicksand, and then into a mass of water, in a time far less than would be sufficient for the escape of a single chariot, or a horseman loaded with heavy armor.