An adrenaline craze where people jump from cliffs or high objects into the sea has been condemned by U.K. emergency services.

"Tombstoning" has claimed the lives of at least 12 people in the United Kingdom in the past few years. In 2005, bodyboarder Harry Dixon from Sydney, Australia broke his legs while tombstoning in west Cornwall.

The Royal National Lifeboat Institute (RNLI) is urging people to boycott the legal sport and is promoting a summer campaign warning of the dangers of tombstoning.

"It's called tombstoning for a reason – get it wrong and you end up with a tombstone," Ray Barton, from the RNLI, told the BBC.

But the sport could receive more followers after fans recently posted a YouTube video boasting their "Tombstone Tour of Scotland" – complete with maps and jump sites.

The video shows three men taking part in six scary jumps, leaping from bridges and cliffs.

"Young people could be watching and attempt to mimic the activity," RNLI's Steve Wills told The Sun.

Footage of one jump shows the adrenaline junkies are so high, they have to avoid seagulls as they plunge into the water.

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