Gwynedd slate mine home to underground zip line
A new underground adventure centre is due to open - but it is definitely not for the faint-hearted.
Zip Below Extreme lies deep in Cwmorthin, a Victorian former slate mine near Blaenau Ffestiniog, Gwynedd.
Using only headlamps for lighting, visitors can walk, abseil and climb their way through five kilometres (3.1 miles) of the mine's tunnels.
The centre boasts what it claims is the world's longest underground zip wire; there is also the chance to "freefall" into a the dark abyss.
BBC Radio Wales reporter Brendon Williams steadied his nerves and headed underground.
13 Mar 2015