The 200-year-old Standedge Tunnel on the Huddersfield Narrow Canal is being given a vital check up by engineers from the Canal and River Trust.

Britain’s longest and deepest canal tunnel – Standedge on the Huddersfield Narrow Canal – is being inspected by engineers.

It is part of routine maintenance work by the Canal and River Trust on the tunnel, which runs three-and-a-quarter miles.

Engineers will spend three days underground inching their way through the dark to carry out the important inspection.

Watch a narrowboat’s journey through the Standedge Tunnel below

High powered lighting will be bought in to illuminate the tunnel roof so that any cracks or deterioration can be identified and repair works planned.

Inside the Standedge Canal Tunnel

Inside the canal tunnel. Credit: Wikimedia Commons

Standedge Tunnel was opened in April 1811 and lies beneath the Pennine countryside.

It took 17 years to dig out and was a costly engineering project.

It claimed the lives of 50 men and cost £123,000 to complete – the equivalent of £8.8 million in today’s money.

Known as one of the Seven Wonders of the Waterways, the tunnel helped keep cargo, such as coal, wood and even horse manure, moving along Britain’s waterways during the Victorian era.

Engineers explore the Standedge Tunnel

An engineer explores the Standedge Tunnel. Credit: Philld/Wikimedia Commons

With no towpath, the horse drawn canal boats originally had to be unhitched and ‘legged’ the length of the tunnel.

This required men to lie on their backs on top of the boat and ‘walk’ along the tunnel roof, moving the boat along with them.

Legging was a challenging and often dangerous job and professional ‘leggers’ were employed to propel laden freight barges through the tunnel.

In its heyday the tunnel operated 24 hours a day and ‘legging’ took about three hours.

But, competition from the railways, which could transport more cargo quicker, meant the Sandedge Tunnel eventually fell into decline.

The last commercial boat passed through the tunnel on 13 October 1916.

Entrance to the Standedge Tunnel at Diggle

Entrance to the Standedge Tunnel at Diggle, Credit: Paul Anderson/Wikimedia Commons

The tunnel was given a new lease of life when it reopened in 2001 after an ambitious restoration project which cost £5 million.

Today, the tunnel is hugely popular with boaters making the epic journey across the Pennines from Yorkshire to Lancashire.

Principal surveyor at the Canal and River Trust, Chris Reynard, said the tunnel is an incredible feat of engineering.

“Standedge Tunnel is an amazing engineering achievement, especially considering it was dug by hand 200 years ago by navvies armed only with picks, shovels and dynamite,” he said.

“It’s strange to think that almost exactly 100 years ago the tunnel was shut down to commercial boats and its restoration described as “impossible”. 15 years after it was reopened it is more popular than ever with boaters and tourists, which is why it’s vital that we carry out this annual check-up,” added Reynard.