THRILL-seeking youngsters hurling themselves into the sea risk drowning or serious injury, authorities have warned.
Police have been advising youngsters in Newhaven and Seaford of the dangers of “tomb-stoning” as the summer holidays loom.
Last year, young people jumped off the large groyne at Splash Point, Seaford.
Sergeant Stuart Mullins said: “Although it may not appear high, there are a great deal of submerged hazards around the groyne and elsewhere along the coast and a potential for very serious injury and drowning.
“Every year, around the UK, people die and I ask parents to emphasise this to children the next time they go to the beach."
The Royal National Lifeboat Institution (RNLI) warned the shock of cold water can make it more difficult to swim.
An RNLI spokesman said: “Tombstoning is a high-risk activity, which involves jumping or diving from a height into water.
“It can be dangerous as water depth alters with the tide – the water may be shallower than it seems, rocks may not be visible and can cause serious injury. “Strong currents can sweep people away.”
He advised people not to tombstone but said those who do can reduce the risk by checking hazards underwater, and checking water depth.
He continued: “As a rule of thumb, a jump of ten metres requires a depth of five metres.
“Never jump while under the influence of alcohol, drugs or peer pressure.
“Consider the risk to others. Young people could be watching and try to mimic the activity.
“Check access. It may be impossible to get out of the water.”