'Bounce below' in an abandoned slate mine in Wales

"Giant trampolines inside a mammoth slate quarry cavern are the latest tourist attraction tipped to bring thousands of thrill seeking tourists to the region.

Bounce Below will open next month at Llechwedd in Blaenau Ffestiniog – the world’s first facility of this kind. The caverns, twice the size of St Paul’s Cathedral, will be lit up in a light show while visitors bounce on giant trampolines linked by a 60ft long slide."

From here and here.