When the prophet Jonah was told by the Lord to go to Nineveh, he went in the opposite direction instead, toward Tarshish (thought to be Spain). Because of his deliberate disobedience in running from the will of God, his life literally went "down hill". Firstly, he went down to Joppa, then down into the bottom of the ship, where he laid down. He then went down into the sea, and finally down into the belly of the great fish (1:3, 15, 17). While down there he repented, expressed his faith in God, and vowed to submit and be obedient to Him (2:7, 9). Then he came up to the place God wanted him to be, and his words were fulfilled: "you have brought up my life from the pit" (2:6b; cf. Ps. 16:10).
The storm that the Lord sent upon the sea, must have been very unusually severe, for the experienced sailors immediately recognized it as being of supernatural origin, and so each crewman (likely from many different countries) called out to his respective god. They wanted Jonah to cry out to his God too, but nothing worked. God heard their cries, but until Jonah confessed his sin and was thrown overboard, as God had purposed, the winds would not die down. When all their attempts had failed, they concluded that someone on the ship was responsible for the storm by having offended one of the gods. Under God's direction, the lot they cast fell to Jonah (cf. Prov. 16:33), who then confessed that he served the Creator, the God of heaven (and thus the God of the elements), but was running from Him. Even the heathen could not comprehend how someone, especially a prophet of God, could possibly disobey the will of the God of heaven.
In response to their question about what should be done to appease his God, Jonah instructed them to throw him overboard. Many understand this as though it indicated repentance and a heroic thing, so that Jonah would not cause others to suffer too. But in light of his initial stubbornness and his attitude after Nineveh repented, it seems likely that Jonah said this because he would rather die than go to the Gentiles in Nineveh. It is hard to tell exactly what Jonah's real intentions were at that point, but it seems that his true repentance did not come until he was in the fish's belly, where he called upon God and quoted many verses from the Psalms (2:2-9). It has been proven that there are several types of sea creatures that are capable of swallowing a man whole. God merely took direct control over one of His creatures and commissioned it to serve His purpose.
Even though Jonah was on the ship in disobedience to God, the Lord was still able to make something good come out of it. All the sailors clearly saw that Jonah's God was the true God and they feared and worshipped Him by offering sacrifices. They also made vows, which were no doubt vows of commitment to serve Him alone (1:14, 16). Jonah, then, was still a witness for God to Gentiles, even though he had been running in the opposite direction in order to not witness to Gentiles. These sailors, in turn, would have taken this story to their homelands and influenced others to serve God as well.
Jonah's message to Nineveh was that the city was doomed; God's wrath would come upon them, not His mercy. It is possible that he did not even preach repentance, yet they still knew enough to repent with the hope that God would change His course of action (3:9). No doubt the people of Nineveh had heard the report from the seamen, and it is likely that some saw Jonah being spewed out alive onto the shore, which gave evidence to the wrath of God, but also to His mercy. It is possible that if it had not been for this astonishing miracle, the Ninevites would not have given heed to Jonah nor sought God's mercy. Interestingly, in this same time period there was a solar eclipse (763 B.C.) and two severe plagues in Assyria (756 and 759 B.C.); these were understood by the ancients as evidences of divine judgment and could have served to prepare the hearts of the people for Jonah's message.
Nineveh was the largest city in the world at that time. It took Jonah three days to walk the extent of greater Nineveh, which included the surrounding suburbs. Much to his surprise and dismay, the people repented, which at that time was expressed by the wearing of ashes and sackcloth (a coarse garment, probably of goats hair). The immediate judgment upon Nineveh was prevented. God forgave them and recognized their faith. Those repentant Gentiles would be among the saints of God who will one day stand to judge the sinful world (cf. Luke 11:32; 1 Cor. 6:2; Matt. 19:28).
Jonah's anger may have been because his message of doom would not be realized, which could damage his reputation as a prophet. Yet the root cause of his anger was that because of God's mercy upon Nineveh, Israel's enemies would be spared. The Lord had to rebuke and correct Jonah for being narrow-minded and nationalistic. Once again, the Lord proved His authority and sovereignty over nature by causing the plant to miraculously shoot up overnight to provide shade for Jonah. The primary reason for the plant, however, was so God could show Jonah his sin, selfishness, and how wrong it was for him to be full of self-pity. God created both plants and people, but only people, with never-dying souls, are given His special attention. Jonah was to learn that the God of Israel did not only care for Israelites. He chose the Israelites so that through them the whole world might be blessed (Gen. 12:3) with the coming of Jesus Christ. The book of Jonah, then, teaches that God cares for heathens (all lost souls) and so must His people.