Rode the Raft
The next step after drilling for the three prisoners was figuring out a way to get across the water without drowning, freezing, or being caught during their escape. The three devised a genius plan which involved a lot of smuggling.
The three plotted to use raincoats to create a small type of raft, and bribed guards to acquire the necessary amount of coats. They then somehow turned all of these raincoats into a small inflatable boat, which is how they would make it back to the American shore.