An 11-year-old boy pulled dead from a canal had been jumping into the waterway with friends, firefighters have confirmed.
Officers received a report on Thursday evening that the boy had been seen entering the canal in Rotherham, South Yorkshire, but had disappeared soon afterwards.
South Yorkshire Fire and Rescue and the Ambulance Service attended the scene and the boy was found in the water at around 11pm.
Gary Willoughby, from South Yorkshire Fire and Rescue, said: "This 11-year-old boy was actually taking part in a pastime that boys of his age call tombstoning.
"Unfortunately it's aptly named. It's jumping from unknown heights into unknown depths of water.
"They tend to jump straight into the water. They don't assess the water temperature, they don't see if there are any dangers hidden under the water - shopping trolleys, cars, anything like that, any reeds they might get tangled in.
"They don't even assess how deep the water is before they jump."
Mr Willoughby added: "It's a very dangerous pastime. Unfortunately this boy lost his life. I have heard of other people that end up in wheelchairs for the rest of their life."
"I'd like to send my condolences to his family at this time.
Mr Willoughby said he was campaigning for line boards to be placed along dangerous watercourses with combination locks that can be unlocked by ringing 999.
There was no sign of police activity on Friday morning at the scene, which is behind the large Parkgate retail park.
It is understood the rescue operation took place in a stretch of the South Yorkshire Navigation close to a path which crosses the canal over a metal bridge.
The path connects the retail park with the Eastwood area of Rotherham, but there are no houses or other buildings in the immediate area.
The bridge over the canal is one of three next to each other also taking the track across the River Don and the main Doncaster to Sheffield railway line, which all run parallel to each other.