A teenage boy died after he lost a rock, paper, scissors bet and jumped into a freezing reservoir.
Sam Haycock, 16, of Rotherham, Yorkshire, was celebrating the end of term with his pals when the tragedy unfolded.
He drowned in Ulley Reservoir, near Rotherham, on May 28 last year after 'cannonballing' from a nearby bridge.
Onlookers heard one of the teens at the reservoir shout 'I'm drowning, I'm drowning', YorkshireLive reports.
An inquest at Doncaster Coroner's Court heard that Sam, a popular boy, had only recently been diagnosed with autism and other complex medical problems and was unable to swim.
Senior coroner Nichola Mundy heard evidence that Sam and his pals had been 'egging' each other on as to who was to make the first jump into the freezing water.
In the end the group of boys, none of whom were strong swimmers, agreed for two of them to play rock, paper, scissors to decide who would go first with Sam losing.
He jumped in but immediately his friends could see he was panicking and one of them, identified only as C, bravely leapt in and tried to save him.
One of several adults who were there at the time, Craig Pennington, said: "I could hear what sounded like young lads laughing and joking around.
"I could see four teenage boys, it sounded like they were getting more excitable. It appeared like they were egging each other to jump into the water.
"One of the teenagers then started shouting: 'Help me, help me'. I went to see what was happening not realising the urgency until I got next to the side of the bridge. It all happened so quickly."
The court heard that one of his friends, only identified as 'C' bravely leapt in to try to save his friend but was unable to do so.
Mr Pennington added: "We assisted the teenager hanging onto the bridge, ('C'), and between us we managed to get him out of the water.
"He kept saying: 'Where's my mate, where's my mate?'"
Another man, Conna Lee King added: "I heard one of the teenage voices shouting: 'I'm drowning, I'm drowning.'"
He said he was about 30 metres from the bridge and ran towards it. He said he helped haul 'C' out. He said: "He asked me to go back in for his mate.
"I replied saying I would go in but I couldn't swim. It all happened so fast."
The court heard a throw line was unsuccessfully used to try to rescue Sam.
A 999 call saw the emergency services arrive at the scene and a firefighter bravely leapt in to try to find Sam but by then it was too late and his body was recovered later.
Kevin Burke, countryside and ecology manager for Rotherham Council, said there were problems with antisocial behaviour in the area.
He said a ranger had been threatened and there had been an occasion when, for amusement, glue had been placed in the locks of the code box for the throw line to frustrate its use.
Asked by the coroner about why floating rings were not available he said it was difficult as they were quite heavy to throw and some antisocial people used them for swimming.
He said the water was 26-30 feet at its deepest and although the first few inches would be relatively warm once you got below the first foot it would be very cold indeed.
At nearby Thrybergh Country Park, there was managed swimming from June/July but even then wetsuits had to be used.
Mr Burke said the antisocial behaviour was a "disgrace" but he had been working with Sam's father Simon on Operation Keep Safe to improve safety standards around the reservoir.
Ms Mundy concluded that Sam died from drowning and his death was an accident.
She said: "Because he didn't have any fear or sense of danger he said he would jump in first.
"The temperature of the water would have been a significant shock to Sam and to Sam's system that would have sent him into panic. His friend's efforts to save him were valiant.
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"His friend was very brave but it simply was not possible him to save his friend despite his best efforts."
And she slammed the behaviour of antisocial people who visit the area and derail the equipment for their own amusement saying this "put lives at risk.
"Rotherham Council has a constant battle to try to ensure that they remain in place."
The hearing was attended by four members of the Haycock family including his father and Sam's mum Gaynor who clutched a photograph of her son with his beloved pet dog Ruby for the duration of the proceedings.
Sadly, the same reservoir claimed another life just a few months later in September, that of 19-year-old Khizar Hayat.
