That's on the way to the Glow Worm Tunnel in Lithgow NSW, its a disused 100 year old railway line in the blue mountains... You can drive through this one but the one with the glow worms in it you have to walk to.
The track in there is easy as but there are several more tracks of varying difficulty in the area... it links up to the zigzag railway :)
Greater Lithgow - Glowworm Tunnel

