This is a simple guide to help you unlock the tower code at the top of the tower on Tangaroa Island.
How to Unlock the Tower Code
Open your journal to the last page to find a white piece of paper with 4 images and street names on it.
This shows you the street names and images of stores that are on that street.
On the piece of paper the last number on the code is on Partisan Road at a store with a life saver.
(As seen Here)
After you do this and find all the codes, go to the top of the tower and enter your code into the panel.