A pair of thrill-seekers were captured on camera somersaulting 80ft into the sea from the top of a helter skelter at the end of a Sussex pier.
The daredevils were seen leaping from the top of the ride at the end of the Brighton Palace Pier on Sunday afternoon as sunbathers packed the beach.
Paul Dunt, of the RNLI South East, warned against dangerous ‘tombstoning’ as there may be rocks or objects in the water.
He said: “The RNLI view on this is that tombstoning is a high-risk activity, which involves jumping or diving from a height into water.
“It can be dangerous because water depth alters with the tide - the water may be shallower than it seems, submerged objects like rocks may not be visible and can cause serious injury if you jump onto them.
“The shock of cold water may also make it difficult to swim and strong currents can rapidly sweep people away.
“Jumpers say they have calculated the risks, but the fear is that their actions may be copied by others who don’t.
“For those who do participate in tombstoning, to reduce the risk, check for hazards in the water.
“Rocks or submerged objects under the sea may not be visible through the surface.
“Check the depth of the water. Remember tides can rise or fall very quickly – it may start off deep enough but can quickly become shallower.
“As a rule of thumb, a jump of ten metres requires a depth of at least five metres.
“Never jump while under the influence of alcohol, drugs or peer pressure.
“Consider the risk to others.
“Conditions can change rapidly and check for access, it may be impossible to get out of the water.”
In 2011 a man in his 20s had to be pulled from the sea after leaping from the pier and in 2015 a drunk man suffered spinal injuries after performing the same stunt.