Read: Jonah's prayer in Jonah 1:17-2:10.
Jonah's kinda peeved - he's been sent to prophesy against Nineveh, but he doesn't want to go. So, in an act of flagrant disobedience to God, he runs the opposite way. Turns his back on God, his mission, his calling and heads for Spain.
God - less than chuffed with Jonah - sends a storm to halt him in his tracks.
The sailors wake Jonah up, only to be scandalised as they find out that he's running away from God. (But they still do everything they possibly can to save him). Eventually they follow his advice and throw him overboard, whereupon he gets swallowed by a huge fish which he inhabits for the next 3 days before heading out (in the words of the Veggie tales) like a human comet [Guys - you might not want to rhyme with comet...!].
And in the belly of the fish, Jonah seems to come to his senses - and repents. (He's still a self-centred, grumpy, racist bigot - but he's making progress).
What does God use to do it?
Three things - Wrath, Mercy and Pagans.