Police have issued a warning after a 20-year-old South Wales man leapt off a bridge, apparently as part of a new online craze known as 'Wetnominate'.
Mobile phone footage posted on Jamie Price's Facebook page shows him running alongside moving traffic at Coed Bridge in the Cynon Valley, before throwing himself off and somersaulting into the water.
Mr Price, from Aberdare, later posted a picture of himself with scratches on his torso, which he said were 'the after-marks of jumping off the bridge'.
The bridge jump video has so far been shared more than 3,000 times from Mr Price's Facebook page, as well as receiving several hundred 'likes'.
'Wetnominate' began with social media users being dared to empty a bucket of water over themselves before nominating others to do the same.
But there are now concerns that it is escalating to dangerous levels.
Commenting on the incident, South Wales Police said: "This individual is putting himself in serious danger.
"Of course, we advise against such reckless behaviour, which could have tragic consequences."
But Mr Price, who is a builder by trade, defended his actions to ITV Cymru Wales.
'Wetnominate' is one of several internet crazes to circulate on social media in recent months.
Earlier this year, the death of 29-year-old Stephen Brookes from Cardiff was linked to 'Neknominate' - in which young people film themselves drinking a pint or more of alcohol and then nominating friends on social networking sites to do the same thing.