Promising young footballer Bockarie Sonnah, 14, was last seen jumping from a tower into Torduff Reservoir in Bonaly Country Park on the outskirts of Edinburgh on Monday.
The group had finished playing at the site and got dressed to go home, but it is claimed Bockarie, a pupil at Firhill High School, decided to jump again.
After it became clear he was in difficulty, his friends contacted the emergency services on their mobile phones and also cycled to the nearby suburb of Colinton to raise the alarm.
Bockarie's body was recovered later that night from the water after a search by police divers. The tower is popular with people who use it to jump into the water despite danger signs and fencing at the pier.
Local angling group Clubbiedean Fishery said the death stood as a warning to other young people. It said in a statement:"A group of local kids who have been swimming in Torduff reservoir for the past few weeks went up. Unfortunately the last to go got into difficulty and due to the remote location he was unable to be saved in time."
A friend of keen Hearts fan Bockarie described him as like a brother. He wrote on social media: You were a great lad, we're all proud of you, sleep tight big man."
Another youngster wrote on social media that his friend had been taken "far too young". He added: "You had the rest of your life ahead of you. You'll be missed so much Bockarie."