A Teenager diced with death in a dangerous summer stunt which emergency services fear will end in tragedy.

Scores of youths have been creating mayhem for rescue crews' resources during the heatwave.

They have been hurling themselves 40ft into the mouth of the busy harbour at Brighton Marina just days after warnings about similar stunts from Palace Pier.

Repeated warnings from police, Coastguards and harbour security staff have failed to stop youngsters risking their lives in a series of summer crazes which are becoming a burden for the emergency services who fear it is only a matter of time before someone dies.

Police say the high spirits of youngsters, and some adults, during the heatwave is leading to carelessness, which is putting extra pressure on emergency services who are called out whenever someone's life is at risk.

Inspector Lawrence Hobbs, of Sussex Police, said: "As far as we are concerned this is extremely dangerous behaviour which puts their lives and the lives of anyone trying to rescue them in danger."

Youths are ignoring the warnings and leaping from the breakwater at the harbour entrance of the marina.

An amateur photographer captured the moment this boy, aged about 14, threw himself from the harbour wall into a stretch of water used by dozens of jet skis, speedboats and yachts each day.

He was one of a dozen youths who gathered on the breakwater on Sunday to take turns to leap from the wall. An onlooker said: "You know if he had paralysed himself or hit someone's speedboat his mum would say he was the victim."

Coastguards, who have been forced to alert boats to the presence of swimmers at one of the busiest times of the year, say such a sheer drop into waters constantly churned up by passing vessels could soon cost someone their life.

Police have been called to the marina several times in the last few days.

At 3.15pm yesterday four youths were discovered swimming in the harbour entrance.

Further down the Brighton coast, a nine-year-old boy who had been drinking was pulled from the sea by Coastguards and paramedics. Police confirmed the child was drunk after being pulled from the water near the Palace Pier.

He had been drinking with a 12-year-old at a groyne nearby. A group of youths were at the groyne at about 2pm yesterday but it was unclear whether the child fell or was pushed.

The boy was unhurt but taken to the Royal Sussex County Hospital because of his condition.

Youngsters continued to jump off the marina breakwater yesterday despite warnings from a boat captain who got close enough to give them a talking to.

A spokesman for Solent Coastguard said: "Jumping off any object into the water is dangerous because you can't see what's underneath the surface.

"But to leap off the breakwater at low tide is a huge jump. You don't have much water beneath you. If you hit water from that height it will sting.

"Even at high tide it's still pretty dangerous, the main concern being you do have quite a lot of movement in that area with vessels sailing in and out of the harbour."

No one at Brighton Marina was available to comment last night but one worker there said: "We warn them all the time. They take no notice. The only time they will stop is when they do themselves some damage."