This tells the story about how Finn came to Ooo in the first place.
It also explains why he is afraid of the ocean.
On a very stormy night, a boat is being hit by huge waves.
Inside, Finn's parents ( Richard and Susan ) are putting things in a crate, while baby Finn slowly walks around.
Susan: Are you sure Richard? The sea is very dangerous.
Richard: It will be alright Susan, this crate will protect him.
Baby Finn falls asleep.
When they were done, they put baby Finn into the crate and go outside.
They drop the crate into the ater, and watch it drift.
Susan: Sea, let these be my last words to my baby before this storm topples the boat over. Goodbye my son, may you do great things!
The crate hits the shores of Ooo, and baby Finn falls out.
He gets up, looks around, and slowly walks towards the forest.
The thing is, this baby is Finn, but he wasn't named that yet.
I put baby Finn so you would know who the baby is.