It is 16,499 feet (5,029 m) long, 636 feet (194 m) underground at the deepest point, and 643 feet (196 m) above sea level.
The Huddersfield Narrow Canal
This canal is one of three that crosses the Pennine Hills and built to provide transport between Huddersfield in Yorkshire and Ashton-Under-Lyne in Lancashire.
The canal is only 20 miles long and due to the nature of the terrain has 74 locks even though the summit tunnel reduced the number of locks needed.
In theory having a summit tunnel to reduce the number of locks means that the journey times should be relatively short. However the tunnel does not have a tow path and when it was first opened it was necessary to lead the horses over the moor to the other end of the tunnel. Meanwhile it was necessary to leg the boat through the tunnel. This involved specialist workers who lay on their backs and used their legs with their feet against the tunnel wall to leg the boat through.
Even with powered boats the tunnel remained a bottleneck and remains so to-day.
It was originally expected that the tunnel would take 5 years to build, but the terrain was more difficult than expected and in the end it was not completed until 1811, 17 years after work first started.
The tunnel was started at both ends, but mistakes were made. The Diggle end was originally several feet higher than the Marsden end, which if not corrected would have led to the longest flume in history. In addition Thomas Telford realised the two ends were not aligned correctly and introduced slight bends to correct for this.
Further information about the building of the canal together with pictures can be found at
this website.
Not long after the canal opened a railway tunnel was built next to the canal. By using side linking tunnels construction work was speeded up by using the canal boats to remove the waste.
A total of three railway tunnels were built and in order to accomodate the last one the canal tunnel was extended to its current length in 1893.
Modern Day Use of the Tunnel
The whole canal had ceased to be a working canal in 1944, but after an extensive campaign the canal reopened in 2001 to leisure craft, including the tunnel.
When the canal first re-opened boats used to be towed through the tunnel by an electric tug. However since 2009 boats now go through under their own power, but a time slot must be
booked in advance and a qualified pilot will be arranged to be on board. If you are nervous about navigating the slight bends you can request that the pilot steers the boat for you.
If you haven’t got your own boat you can still enjoy a half hour trip into the tunnel from the
visitor centre at the other end of the tunnel at Marsden. The trips run every day except Mondays (but do run if it’s a Bank Holiday or school holiday) between March and November.
If you’re feeling more adventurous and want to travel through the whole tunnel, then on every other Saturday there are 2 hour long trips through the whole tunnel from both the Marsden end of the tunnel and this location at Diggle.
The gates at this Diggle portal have a silhouette sculpture attached showing a canal boat being legged through the tunnel. There is also a blue plaque honouring the engineer Thomas Telford who designed the nearby locks and corrected the tunnel misalignment problem.