Map: Mittagong. We'll park the cars at the picnic area at 623863 which is off the Wombeyan caves road near Welby. Walking along a track we descend to visit Forty Foot falls at 642873 before exploring along the Nattai river and ascending at 637891. Part of the walk is along the old Box Vale railway with some dramatic cuttings and a tunnel. Half on track and half off-track.