You can generally walk in the mine standing up (for heights under ~1.80m). There is only one area where you have to half-crawl.
There are two exits that go elsewhere, one in the forest (east) and one in the wall (north).
There are several intersections, some of which clog up.
To reach the most spectacular exit (wall - north), follow the hubs in the intersections: they will be placed in the form of a barrier if NOT that is where you have to go.