Elliot Peacock, a member of Eastwood District Scouts in East Renfrewshire, was among youngsters jumping into water under instruction on a gorge-scrambling trip at the Lillaz Falls, 1800m above sea level in the Gran Paradiso National Park, on Sunday.
About 40 scouts were enjoying the second day of a nine-day trip in the area north of Turin when Elliot took ill.
Fellow classmates left flowers at the foot of a tree outside Eastwood High School, where he was a pupil, after details of the tragedy emerged yesterday.
James Hay, 14, said: "I can't believe Elliot's not coming back. He was really looking forward to the holiday. He loved adventure and was always full of life.
"He was a really funny guy and he made everyone around him happy. We will miss him and when I heard what had happened I was really upset.
"Elliot was very popular and everybody liked him. He made you feel happy just being around him.
"We were in S3 and moving up to S4 after the school holidays. He went on a lot of the school trips as well. He loved going abroad."
James and other friends of Elliot, 14, of Newton Mearns, made arrangements to lay flowers in their school grounds via social networking sites and sympathy cards were also left there for his parents.
The trip organiser, Acorn Adventure, described gorge scrambling as walking up and down a gorge and jumping from low level into pools. It was during one such jump that Elliot lost consciousness.
Instructors supervising the adventure holiday battled to revive him and a helicopter arrived on the scene within minutes but the young Scout was declared dead at the scene two hours later.
It was reported that early results from a pathologist's examination suggest Elliot may have been killed by whiplash after the back of his helmet hit the water, fracturing his cervical vertebra.
Delfina Viglione, an officer investigating the accident, was quoted as saying: "At that point the water is three metres deep and therefore it is impossible he hit the bed. Other medical tests will be carried out to determine the exact cause of death. Only then will one be able to reconstruct what happened."
Elliot's father Scott, a logistics company operations manager, and his mother Colette, a chartered accountant, flew to Italy to identify their son's body and bring him home.
A relative of the victim said: "We don't want to say anything just now."
Acorn Adventure said it was the second time Elliot had jumped into the water when they noticed something was wrong and rescued him but it was too late.
A spokesman for the firm said: "The group were jumping from a height of approximately 60cm (2ft) into the water, where instructors were waiting for them, as is normal. Water conditions were optimum for the activity and the weather was warm and sunny.
"As this participant entered the water for the second time, it was obvious to the instructors something was wrong, so they rescued him from the water immediately.
"Instructors who are trained first-aiders and nurses who were also at the scene began CPR and continued until the air ambulance arrived 10 minutes after being called. Very sadly, they were unable to resuscitate him."
Elliot was a member of the Pegasus Explorer Scout Unit linked to the 35th Glasgow Scout Group.
The Scout Association said in a statement: "We are devastated that a young person has died and our thoughts and prayers are with the family and friends of the young person at this time.
"The Scout Association continues to support Elliot's parents, the young people and leaders who are part of the event. We will continue to work with Acorn Adventure to establish if there are any lessons to learn from this tragic incident."