In pictures: Bouncing beneath Blaenau
It's already home to the world's longest zip-wire, now Gwynedd boasts what is believed to be the world's largest underground trampoline in the abandoned Llechwedd slate quarry.
Visitors will be taken deep inside the mountain via train to discover a set of three enormous trampolines, suspended like giant spider's webs.
The cavern is illuminated with incredible neon lights, with the trampolines interconnected by stairways and slides. The atmospheric cavern is twice the size of St. Paul's Cathedral and the biggest slide reaches 60ft high.
Intrepid visitors will be supplied with cotton overalls and a safety helmet before embarking on their journey into the cavern.