Lees Moor Tunnel is an abandoned tunnel on the former Great Northern Railway line between Queensbury and Keighley in West Yorkshire, England. The former dual track tunnel is just north of the village of Cullingworth in West Yorkshire and when built was 1,533 yards (1,402 m) long. Due to the pitch black inside and the squealing of the wheels on the 1 in 50 radius curve, drivers nicknamed it the 'Hell Hole'. After closure to passengers, the tunnel was used in experiments involving the effects of smoke inhalation and cancer.