The miracle of Jonah surviving at sea points us to the miracle of Jesus' death and resurrection. It also teaches us that:
You can't run away from God!
You can't stop the sovereign will of God!
Selfishness can keep us from obeying God.
God loves even the worst sinners.
Jonah 1-4, Matthew 12:38-40, Romans 10:13-15, Matthew 16:18, Matthew 16:24, 1 Timothy 1:15