Llechwedd Slate Caverns

Llechwedd (Welsh pronunciation: [ɬɛχˈwɛð]) is a visitor attraction near Blaenau Ffestiniog, Gwynedd, Wales.

The attraction also incorporates Mountain biking tracks, Zip-lines and giant underground trampolines.

The 2 ft (610 mm) narrow gauge Miners' Tramway, opened in 1972 under the name "Quarry Tours",[1] was a railway travelling 800 metres underground.

The trains were hauled by battery-electric locomotives and travelled through tunnels and into a series of quarry chambers.

[6][7] In January 2019 a television crew took over the caverns for a week to film the world's first ever underground games show, Y Siambr, broadcast later in the year on S4C.