A high-speed run down the slope of a spillway and then into the standing waves at the bottom.
It doesn't look particularly brilliant or even scary really--as long as you're facing forward, you're good.
That the dam owners have condemned the attack, well, that what they have to do, innit? You can't just open your doors to anyone, 'cause then you've got a lawsuit on your hands.
Anyway, footage and article are here at the BBC. The photos are by James Davies, Swansea, and are posted in a sequence over at the Beeb.
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