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Cave transformed into giant trampoline

10 July 2014 Last updated at 08:17 BST

The world's largest underground trampoline has been unveiled in a cave in Blaenau Ffestiniog, North Wales.

The unused cavern was once used as a slate mine but has been transformed by installing three giant trampolines.

The trampolines are reached by train, with each linked by a 60ft (18.28m) long slide.

Tomos Morgan reports.