The story of Jonah is an interesting one in that it presents a familiar albeit impossible narrative. The story recounts that Jonah was charged by God to go to the sinful city of Nineveh to cry out against it. But Jonah was not too thrilled at the idea of going to Nineveh and indulge himself in rabble-rousing, so he hopped the first available ship out of Joppa that was headed for Tarshish in attempt “to get away from the service of the Lord.” The Lord sends a storm that frightens the ships sailors and being superstitious they figure the gods are punishing them. This is when Jonah explains to these frightened men that he is to blame for the storm and that they should throw him overboard for their own protection. The sailors refuse to follow Jonah's advice but when the storm persists they reluctantly throw Jonah overboard and this is when a giant fish swallows Jonah and carries him in its belly for a period of three days until it arrives at the shores of Nineveh at which point the fish vomits Jonah out.
This is a fantastic story that contains a very unbelievable narrative. Jonah was swallowed by a fish or a whale as some contend and yet there isn't a fish/whale in existence that could swallow a man whole. Some have suggested that the Sperm Whale could have been the culprit however this variety of whale, which has the stomach to accommodate a human, does not possess a throat large enough to swallow a person. Further, no aquatic species, including whales, have air space in their stomachs which would be necessary for breathing and the story says that Jonah prayed in the belly of the animal which means he had to breathe. This story presents many problems and the question we need to address is whether the story is meant as a literal event or if the story represents a legendary tale that is meant to be taken as an analogy.
Rarely considered in Judaism is the fact that in older Greek mythology the demigod Herakles (Hercules) was also swallowed by a whale, and he too had departed from Joppa. Add to this curious coincidence that it was at Joppa also where, in Greek myth, Andromeda was bound beside the sea as a sacrifice to a sea monster. So where was Joppa located? In Greek myth Joppa was located in Aethiopia. Aethiopia is the Greek equivalent of the Hebrew geographic location called Kush. Joppa was the capital of that region and a seaport city.
Like many Biblical stories, there are preceding myths of other cultures upon which they are based. This means that the book of Jonah is another tale utilizing coded elements from pre-history wisdom. The Sea Traders of the time were Phoenicians, and like their close kin the Philistines, they worshipped Dagon, who was depicted in his statuary as a Fish God. Recall that another story occurs in 1 Samuel relating that after the Philistines captured the Ark of the Covenant and placed it inside the Temple of Dagon that twice the effigy of Dagon fell before the Ark. The Philistines were Israel's premier enemy in the ancient world and the Ark story is a narrative crafted to demonstrate that Israel's God is greater than the God of the Philistines. The Jonah story is a narrative crafted from earlier stories because it served the same purpose- demonstrating the superiority of Israel's God above the Phoenicians, which was the same idol of the Philistines.
Is it possible that any part of this legend might be literally true? It's improbable but a bit of deductive reasoning with a healthy dose of speculation can be applied to maintain a literal reality.
Let's surmise that Jonah took passage on a Phoenician ship, to escape God's mission for him. The Phoenicians had great carved prows on their ships, in the likeness of their Gods. This we know, from Archeological remains. So what happens when the Phoenicians realize that Jonah is the spokesperson for the Israelite God- YHVH?
Would they throw him overboard? It's very doubtful and the narrative of the story describes their reluctance. Seamen are superstitious, but not that superstitious. They threw him into the belly of the great fish, which was their ship as it was in the image of Dagon (Fish god) and likely named after him. Jonah remained in the ships belly for the designated "quarantine" spell of 40 days (also the designated fasting time for Holy festivals). Then fearing the wrath of his God, as soon as the proper formalities were out of the way, they threw him up from the fishes belly, at first landfall. Being in the belly of the ship he likely remained wet through the duration of the trip which caused his skin to prune and whiten in its appearance.
It's easy to see where over the years, even though the details of the story may have been confused, the allegory still remains at its heart.