"Then the Lord commanded the fish, and it vomited Jonah up onto the dry land."

God is still in control.

If you understand God's patience, then you realize how long God waited to release Jonah from this trial.  Jonah went through the repentance process we see in chapter two.  Once Jonah verbalizes his understanding that salvation belongs to God, God releases him.

If you understand God's omniscience, you realize that God's purpose in making Jonah wait and suffer was to see true repentance.  That God knew all along how long it would take Jonah to come to the truth - even that God knew Jonah WOULD come to the truth.

If you understand human nature, you understand that we all have the choice to turn to God, sometimes we must see the other side before we can believe God is simply gracious.

I don't know if Jonah understood any of that - but I do believe that at the point of fish vomit, Jonah realized and remembered that God is in control.

Maybe that's all we need to understand.