Use newDirName = os.path.abspath(dir)
to create a full directory path name for the subdirectory and then list its contents as you have done with the parent (i.e. newDirList = os.listDir(newDirName)
)
You can create a separate method of your code snippet and call it recursively through the subdirectory structure. The first parameter is the directory pathname. This will change for each subdirectory.
This answer is based on the 3.1.1 version documentation of the Python Library. There is a good model example of this in action on page 228 of the Python 3.1.1 Library Reference (Chapter 10 - File and Directory Access). Good Luck!