Translation:Do you want to go on a plane or on a boat?
Like in English, "to go" and "to leave" don't have the same meaning and the verb "ir" is usually translated to "to go".
Ex: "Quero ir para casa" "I want to go home." "Quero sair de casa" "I want to leave home"
So, when the action is going to (somewhere) you should use "ir", but when the action is to leave (somewhere) you should use "sair".
I hope it has been helpful. Good luck
And you understood it well, but as you know, words like pronouns, prepositions, etc...there are some situations that can't be translated literally, and here you can't use "por".
Ex: "This was made by you" - Isto foi feito POR ti (using "de" it's wrong) "I came by car" - Eu vim DE carro (using "por" it's wrong)
I'm trying to find an easy way to explain it...but, well, I hope it has been helpful. Even If you don't understood what I tried to show here, I sure with some exercises you'll understand it easilly.