I am struggling with some SharePoint 2013 navigation structure. What I need is something like this below. That is, a navigation in the left side with three levels, that expands. I think that this should or could be solved with some Subsites instead of pages, but I am not able to hit the right structure.
Do anybody have some ideas, or advices on how to proceed? It has to be out of the box, or should it be coded, it has to be a minimum amount of developing.