North Wales continues to develop as a leading adventure-activity destination, with the opening of the world’s largest fully underground zipline course.

In the vast Llechwedd Slate Caverns, Zip World’s latest attraction is a 10-line course that takes visitors on an aerial adventure through five caverns, some big enough to fit 75 double-decker buses.

The ziplines are interspersed with rope bridges, balance beams, tunnels and stretches of via ferrata: a mountaineering aid in which a harness is clipped to a cable running along a precipice.

Suitable for children as young as 10, the experience lasts around three hours. The walls of the cavern are illuminated by LEDs, transforming the dark cave into a vibrant environment.

The course was built over a period of 12 months, with workers swinging 100ft from the ground using an intricate network of wires and pulleys. Bottles were used for toilet breaks to “increases efficiency”.