The coroner has told the father of the Stoke-on-Trent teenager Ryan Evans "we all feel for you, nobody can understand how you feel".
The hearing was told that the 13-year-old and his friends had decided to meet up after school at Westport Lake on Monday 25 June, during "the hottest summer for many years".
Ryan briefly returned to his Burslem home to get changed and pick up a chocolate bar and some crisps, then asked his father Glynn Evans to help him get his bike.
He was told to be back for tea at 6pm and left the house at 3.45pm.
It was the last time his father saw him alive.
The hearing was told Ryan had not made Mr Evans aware he was planning to swim, probably because he knew he was not allowed to do so.
Having reached the lake, the group of friends stripped to their boxers and got into the water near "the dug out area", often used by people going fishing.
Three of the boys, including Ryan, decided to swim right across the lake to the other side.
He got into difficulties in the middle and, despite his friends' efforts to save him, disappeared under the water.
An eyewitness who went to the park for a walk at about 4.10pm reported seeing the three boys, one of whom was clearly struggling.
He yelled at them not to carry on swimming across and, with another man, rang 999.
The two remaining boys took about 10 minutes to swim back.
An extensive search was subsequently carried out, with teams facing extra difficulty because of problems seeing under the water.
The coroner heard Ryan's body was found by divers from Nottinghamshire Police almost 48 hours later, after being spotted by a police helicopter.
The hearing was told that, although the teenager he achieved medals in swimming at school, he was not actually a particularly strong swimmer.
North Staffordshire Coroner Ian Stewart Smith reiterated the dangers of swimming in places like Westport Lake, saying the temperature and the depth could vary, and there were "hidden hazards" such as weeds.
He added that even good swimmers could get into trouble there and that most people who did swim in such places would wear wet-suits, whereas the boys had just been in their underpants.
Mr Smith said a post mortem examination carried out on Ryan's body had concluded "death by immersion, drowning in other words".
He recorded a verdict of Accidental Death, and commented that there was nothing more to suggest that this was anything but a tragic accident.
Detective Constable Matthew Jones told the hearing the council had informed him that warning signs had been put up, but when, last month, he retraced the path the boys would have taken, he did not see any signs there, apart from a new one on the fishing platform.