Not many know that under the ground of Blaenau Ffestiniog, Wales, hides a cavern twice the size of St. Paul's Cathedral. What's so special about this 176 year old disused slate mine? It's been magically transformed into a subterranean playground full of trampoline-like nets connecting vast naturally formed chambers, also linked by walkways, slides the height of two double decker buses and trampolines. Bounce, climb and slide like children while exploring this incredible underground attraction, lit up with twinkling technicolour lights to add to the atmosphere