Local legend has it, following a culvert in a forest within Bishop Auckland North East England leads to an off shoot in the brick wall, aptly named Smokies Cave by the locals. It features photogenic brickwork and wooden supports with some midly low crawls.

I believe its an old coal mine.

I've been in this mine up until a point where a Sump appears however I've not been to the North East in quite a number of years.

I'll share the photos I have later on of this.

Has anyone else been down there and have experience

I know someone who went within the last few weeks, its certainly still accessible.