It is claimed to be the first underground game show, filmed entirely in the Llechwedd Slate Caverns of Blaenau Ffestiniog, North Wales.

[4] In each programme two teams of three players compete to win challenges on the four levels of caverns, via netted cages and zip wires suspended inside the caves.

Examples of the challenges include: After reaching the bottom of the cave, the winning team has to solve puzzles to crack a code, to be able to escape to the daylight.

[3] The programme is produced by Boom Cymru and the idea was first conceived after one of the executive producers and his family visited Bounce Below's deep cave trampoline centre, at the Llechwedd Slate Caverns in Blaenau Ffestiniog.

With mainly unstable trampoline floors, camera crew were required to hang from the ceilings to get a steady footage.