History bit stolen from Wiki - http://en.wikipedia.org/wiki/Standedge_Tunnels
The Standedge Tunnels (Standedge is normally pronounced Stannige) are four parallel tunnels that run beneath the Pennines at the traditional Standedge crossing point between Marsden and Diggle, on the edges of the conurbations of West Yorkshire and Greater Manchester respectively, in northern England. There are three railway tunnels and a canal tunnel (on the Huddersfield Narrow Canal). The canal tunnel is the longest and oldest of the tunnels, and holds the record as the longest and highest canal tunnel in Britain. All four tunnels are linked by cross-tunnels or adits at strategic locations within the tunnels. The adits allowed the railway tunnels to be built much more quickly by allowing 'waste spoil' to be removed by boat and reducing the need for shafts for construction. Of the railway tunnels, only the tunnel built in 1894 is currently used for rail traffic. Closed in 1943, the canal tunnel was re-opened in May 2001. The Standedge Tunnel Visitor Centre, at the Marsden end of the tunnel, serves as a base for boat trips into the canal tunnel and hosts an exhibition which depicts the various crossings.
The central tunnel seems to be a cut through for the railway staff, I had to dodge down side tunnels quite a few times in the pitch black as jeeps drove past!
One of the Jeeps was parked up next to a tunnel to the canal, once it shifted I dashed over and had a nosey but didn't stick around to take pics
Drain down to the Canal