There is a trick thanks to which you can explore the game. I have found at least two ways to get out of the map but only in chapter 3... for now. Main steps are listed below.

1. In the chapter 3, go to this bar stool where tobacco pipe lies and and try to get through it. Try from different angles. You should be thrown up to the sky. direct link

2. I know, the fish are amazing but when you finally want to come back on that ship, there is a possibility. I have found a place where you can back to prow. Go to lower hull and try to get through it from different angles. direct link