Is located at the northern end of Glowworm Tunnel Road, accessed via Clarence or State Mine Gully, Lithgow. It was here that the old Wolgan Valley Railway line wound around the base of the cliffs, then through a tunnel approximately 400m long. The creek near this tunnel is called Tunnel Creek and has also been referred to as Penrose Creek. This was the second tunnel constructed in 1907 for the railway to Newnes from Newnes Junction, off the Main Western Line. The first tunnel is now vehicular access to the Glowworm Tunnel and about 3km closer towards Lithgow. The Glow Worms are a larval stage of a harmless, luminous species of fungus gnat, family Arachnocampa. Spelling has varied on different maps, such as Gloworm Tunnel; Ben Bullen Topo, first edition, Glowworm Tunnel Road; Cullen BullenTopo, second edition, as well as Glow Worm Tunnel and Glow-worm Tunnel, websites.