The children of Israel got to the Red Sea and had nowhere else to go. They felt trapped as the Egyptians had been pursuing them. If God did not show up that was it.
Water was in front of them; a humanly impossible situation.
They had come to the end of themselves; there was nothing they could do but cry unto the Lord.
Heavens agenda in any situation is several steps up higher than what we are thinking. Kevin Zadai.