How Did Moses Part the Red Sea?

How Did Moses Part the Red Sea?

The science of tides may have saved the Israelites from the Egyptians

By Bruce Parker in the Wall Street Journal

Ridley Scott’s “Exodus: Gods and Kings,” which opens in movie theaters across the country Dec. 12, will include, of course, the most famous of all biblical miracles: the parting of the Red Sea. But its depiction will look quite different from the one in Cecil B. DeMille’s 1956 classic “The Ten Commandments.” In the earlier movie, Charlton Heston as Moses parted the sea into two huge walls of water, between which the children of Israel crossed on a temporarily dry seabed to the opposite shore. Pharaoh’s army of chariots chased after them only to be drowned when Moses signaled for the waters to return.

Mr. Scott has said that his new version of the story will have a more realistic and natural explanation of what happened and won’t rely on Moses to bring forth God’s miraculous intervention. He has decided to have the waters “part” as the result of a tsunami caused by an earthquake. Before a tsunami strikes, coastal waters often recede, leaving the seabed dry before the giant wave arrives.

But there are problems with this version of the story, too. The period during which coastal waters draw back before a tsunami usually lasts only 10 or 20 minutes, too little time to get all the children of Israel across the temporarily dry seabed. Also, there would have been no way for Moses to know that the earthquake and tsunami were going to happen, unless God told him. That’s fine, but then the story would retain some element of the miraculous.

There is a much better natural explanation for how a temporary path across the Red Sea could have been revealed. It involves the tide, a natural phenomenon that would have fit nicely into a well-thought-out plan by Moses, because Moses would have been able to predict when it would happen.

In certain places in the world, the tide can leave the sea bottom dry for hours and then come roaring back. In fact, in 1798, Napoleon Bonaparte and a small group of soldiers on horseback were crossing the Gulf of Suez, the northern end of the Red Sea, roughly where Moses and the Israelites are said to have crossed. On a mile-long expanse of dry sea bottom exposed at low water, the tide suddenly rushed in, almost drowning them.

In the biblical account, the children of Israel were camped on the western shore of the Gulf of Suez when the dust clouds raised by Pharaoh’s chariots were seen in the distance. The Israelites were now trapped between Pharaoh’s army and the Red Sea. The dust clouds, however, were probably an important sign for Moses; they would have let him calculate how soon Pharaoh’s army would arrive at the coast.

Moses had lived in the nearby wilderness in his early years, and he knew where caravans crossed the Red Sea at low tide. He knew the night sky and the ancient methods of predicting the tide, based on where the moon was overhead and how full it was. Pharaoh and his advisers, by contrast, lived along the Nile River, which is connected to the almost tideless Mediterranean Sea. They probably had little knowledge of the tides of the Red Sea and how dangerous they could be.

Knowing when low tide would occur, how long the sea bottom would remain dry and when the waters would rush back in, Moses could plan the Israelites’ escape. Choosing a full moon for their flight would have given them a larger tidal range—that is, the low tide would have been much lower and the sea bottom would have stayed dry longer, giving the Israelites more time to cross. The high tide also would have been higher and thus better for submerging Pharaoh’s pursuing army.

In ‘The Ten Commandments,’ Charlton Heston as Moses parted the sea into two huge walls of water, between which the children of Israel crossed on a temporarily dry seabed to the opposite shore. Everett Collection

Timing would have been crucial. The last of the Israelites had to cross the dry sea bottom just before the tide returned, enticing Pharaoh’s army of chariots onto the exposed sea bottom, where they would drown as the returning tidal waters overwhelmed them. If the chariots were expected to arrive before the tide came back in, Moses might have planned some type of delaying tactic. If the chariots were expected to arrive after the tide came back in, he could have gotten the Israelites across and then, at the next low tide, sent a few of his best people back onto the temporarily dry sea bed to entice Pharaoh’s chariots to chase them.

The Bible mentions a strong east wind that blew all night and pushed back the waters. Ocean physics tells us that wind blowing over a shallow waterway pushes back more water than a wind blowing over a deep waterway. If a wind did by chance fortuitously blow before the Israelites crossed the Red Sea, it would have had more effect at low tide than at any other time, uncovering even more sea bottom.

Such a wind would surely have been assigned to divine intervention, and over the centuries, as the story of the Exodus was retold, that aspect would have overshadowed Moses’ careful planning to take advantage of the low tide. But Moses couldn’t have predicted the suddenly beneficial wind, so he couldn’t have based his plan on it. His timing had to be based on a tide prediction.

When Napoleon and his forces almost drowned in 1798 at the northern end of the Gulf of Suez, the water typically rose 5 or 6 feet at high tide (and up to 9 or 10 feet with the wind blowing in the right direction). But there is evidence that the sea level was higher in Moses’ time. As a result, the Gulf of Suez would have extended farther north and had a larger tidal range. If that was indeed the case, the real story of the Israelites’ crossing wouldn’t have needed much exaggeration to include walls of water crashing down on the pursuing Egyptians.

One more piece of evidence is worth citing. As it turns out, my suggestion that Moses could have planned to cross the Red Sea at low tide isn’t entirely new. The ancient author Eusebius of Caesarea (263–339 A.D.) cites two versions of the story of the crossing of the Red Sea as related by the Hellenistic historian Artapanus (80–40 B.C.). One version, told by the people of Heliopolis, is similar to the account in the Bible. But in the second version, told by the people of Memphis, “Moses, being acquainted with the country, waited for the ebb and took the people across the sea when dry.”

If the tide was indeed involved in Moses’ “parting” of the Red Sea, it has to qualify as the most dramatic and consequential tide prediction in history.

—Dr. Parker is the former chief scientist of NOAA’s National Ocean Service and is currently a visiting professor at the Stevens Institute of Technology. He is the author of “The Power of the Sea: Tsunamis, Storm Surges, Rogue Waves, and Our Quest to Predict Disasters.”