Underground trampoline illuminated in blue light
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Underground trampoline opens in an old Welsh mine

10 July 2014 Last updated at 11:55 BST

An old mine in Wales has been converted into a giant underground play area.

The trampoline, underground in Blaenau Ffestiniog, is twice as big as St Paul's Cathedral.

BBC Wales reporter Tomos Morgan jumped at the chance to go and have a bounce.