Trail running is an endurance sport that takes place through natural terrain like wooded and mountainous areas. Participants in the Glow Worm Tunnel Trail Marathon compete in a range of races over 2 days including half marathons and a full marathon. The event is around the Newnes historical region in the Wolgan Valley, north of Lithgow. It is conducted in a variety of terrains, including creek crossings, sections of long single trail, steep mountain trails, old mine cuttings, ruins, some long forgotten railway easements and through the Glow Worm Tunnel.