A two-mile stretch of the Meanwood Beck is culverted as it runs through the city centre, and a series of subterranean tunnels carry the stream underneath roads, the bus station and the railway.
The river eventually joins the Aire near Leeds Dock, between Crown Point and the Royal Armouries.
In this video, urban explorers who belong to the Leeds Historical Exploration Society take viewers on a tour of this fascinating underground world.
Meanwood Beck begins in Adel, and winds its way through the Meanwood Valley to Sheepscar. Its volume of water has been reduced in recent decades due to improved drainage systems.
In centuries past, the beck powered Leeds's corn mills, and supplied water for chemical works and tanneries. It runs alongside Sugarwell Court, a former leather workshop which is now a university halls of residence.
In 1999, the watercourse was hit by an ecological catastrophe when an oil tank at the university's Bodington Hall site was overfilled, spilling 10,000 litres of oil into the beck.