Heartbroken family and friends have paid tribute to Jack who had just finished his last year at Longdendale High School.
Flowers have been placed near to where his body was recovered from the River Etherow, in the Broadbottom area of Hyde.
One message left at the scene said: “Jack I hope you rest in peace mate. Sleep tight xxx.”
Friends have been posting comments on social media paying tribute to the teenager.
“You always cheered me up and put a smile on my face. I am gutted it doesn’t seem real. Can’t believe we spoke this morning and now this happened just can’t stop crying. I’ll never forget you. Love you so much Jack Pullen.”
At the scene bouquets of flowers were tied to a post.
One card read: “To Jack always in our hearts and thoughts , lots of love Family XXXXX.”
Another said: “Jack, Heaven has gained a perfect angel and we’re all left wondering why. Such a beautiful kid. Jack we are all gonna miss you so much. Love you always, Lisa XXX.”
Detective Inspector Andy Sandiford of Greater Manchester Police said: “We have launched an investigation into this tragic incident which appears to have begun with a group of friends playing in the river on a hot summer’s day.
“While we don’t yet know for sure what happened, we understand the water appeared calm and shallow, but there may have been strong undercurrents and hidden hazards beneath the surface.
“A team of detectives are investigating the incident and have concluded that there are no suspicious circumstances surrounding the boy’s death.
“The family of the boy are being supported by specially trained officers during this difficult time.”A spokesman for Greater Manchester Fire and Rescue Service confirmed they also attended the scene and assisted the police operation with the water rescue unit and technical response unit.
Schoolchildren had just broken up for the summer holiday, and a man who lives in one of the properties said youngsters often jump into the water when the weather is warm.
He said: “Everybody on the road is upset because we’ve seen them doing it. It’s like a sign of summer seeing kids jump in and having a laugh.
“One of my neighbours was first on the scene. They found a distraught 16-year-old wondering where his mate had gone.”