The 14-year-old Eastwood High pupil — a member of the 35th Crookfur Scouts — was on a gorge scrambling trip at the Lillaz Falls, Gran Paradiso Park, led by Acorn Adventure.
The company has stated: “All participants were wearing buoyancy aids, wet suits and helmets, as is standard.
“As yet, it is unclear why Elliot lost consciousness as he entered the water.
“Although he was immediately rescued from the water and given CPR, tragically, he could not be resuscitated.”
Elliot’s parents have flown to Italy, where police are investigating the incident.
Stuart Maxwell, Eastwood High head teacher, said that the school is “profoundly saddened.
“Elliot was a genuinely lovely boy. He did well in all his subjects, particularly in physics, enjoyed PE, played guitar, and had a wide circle of friends.
“We have been deeply moved to see so many of Elliot’s friends and fellow pupils arrive at the school to lay flowers and leave cards in tribute to him.
“There will be the opportunity for pupils and staff to sign a book of condolence at the start of term and record their memories of Elliot. All our thoughts and prayers are with his family.”
A spokeswoman for East Renfrewshire council added: “Our priority is to provide support to the year group and to the family while we wait for news on the circumstances of this tragic incident.”
Paying tribute to Elliot on Facebook, Marion Mackay said: “Such a tragic thing to happen. The family have my prayers.”
Joanne Murphy added: “My little boy remembers him helping the cubs. Condolences to his family.”