Police received a call at 12.32pm on Tuesday about the boy – who was in High Dam Tarn near Lake Windermere.
Fire crews, the ambulance service and mountain rescue were deployed, and farmers helped carry their equipment over rough terrain.
A search of the water and shoreline ended with a body being recovered just after 10pm last night.
The incident is not being treated as suspicious, police said.
Read more from Sky News:
British teen Orla Wates dies in Vietnam
Bill Gates to testify in Epstein probe
Superintendent Patrick O’Hara, from Cumbria Constabulary, said: “The thoughts and condolences of the entire rescue team are with the male’s family and friends, who are being supported by detectives.
“I would also like to thank local farmers who supported the operation, conveying first responders and equipment off-road to the search area.”
