The public is being given a rare chance to enter the hidden world of Sheffield’s underground rivers amid proposals to open up again the waterway that gave the city its name.
Sheffield developed around the confluence of the River Sheaf and the River Don, but the Sheaf has been hidden away since the mid 19th century in a series of dramatic Victorian tunnels.
The massive culverts run directly under the railway station and city centre streets culminating in a huge vaulted, brick “cathedral” universally referred to as Megatron.
The urban caving tours are being led into the darkness as part of the Sheffield Adventure Film Festival (ShAFF), which runs from March 22 to 24 in the Showroom Cinema – one of the buildings built directly over the Porter Brook.

The Castlegate area, where the River Sheaf flows out of the darkness and into the River Don, is currently the centre of a massive redevelopment project which has included a bid to excavate and reveal the remains of Sheffield Castle.
As part of the redevelopment, the city council is hoping to open up the last few hundred metres of the River Sheaf – from Megatron to the Don – in a park which would be called Sheaf Field.
Simon Ogden, who heads up the Castlegate regeneration and is also the chair of the Sheffield Waterways Strategy Group, hopes that this would be the just the beginning.

He said: “I’m here to celebrate these rivers and to start to campaign to rescue some part of them from underground obscurity.”
Speaking in Megatron, Mr Ogden said: “The way is rises up it like a cathedral. It’s so impressive.”

