| Official Name: | Tunnel No 2 |
| Line: | Newnes railway line |
| Location: | Newnes plateau |
| Startwork: | 1906 |
| Closed: | 1932 |
| Operator: | Commonwealth Oil Corporation |
| Traffic: | train |
| Construction: | June 1907 |
| Length: | 20chain |
| Notrack: | single |
| Grade: | 1:25 |
The Glowworm Tunnel is a disused railway tunnel between Lithgow, New South Wales and Newnes, New South Wales, Australia. It is notable for its resident glow-worms, the bioluminescent larvae of Arachnocampa richardsae, a type of fungus gnat.
The 20chain tunnel[1] was bored through the sandstone in 1907 as part of the Newnes railway line that served the Newnes oil shale mines that operated during the early 20th century. The railway was closed in 1932 and the rails were pulled out of the tunnel.
The tunnel is now contained within the Wollemi National Park and is a popular attraction for bushwalkers and tourists. Outside the tunnel, the area features spectacular gorges, caves and scenery. The site is maintained by the National Parks and Wildlife Service. On the south side of the tunnel, a large gap in the road prevents vehicular access. According to some sources, this gap was created deliberately to keep cars out of the tunnel, because the exhaust fumes would have killed the glow-worms. On the north side of the tunnel, a track leads to Newnes.
Access to the tunnel is via several routes: