This heart-wrenching video captures the last moments of a boy jumping into the water and having fun with friends before he was swept out to sea.
Furkan Yildirim and his two pals are captured on a smartphone video as they jump off a concrete pier into the cool water.
The 17-year-old belly-flops into the water a few feet below but is seen swimming strongly after he bobs up
The camera pans around to where the other two lads have also jumped in, and they are seen swimming towards Furkan.
One of the boys jokes: “If you drown we will save you.”
But then Furkan disappears from view and the recording ends shortly afterwards as the youngsters become concerned for his safety.
The other two safely got back to dry land.
Emergency services were called and divers searched for Furkan, who was with his pals in the Bebek quarter of Istanbul in north-western Turkey on Saturday, July 15, at around 5pm, but found nothing.
His parents made an emotional plea for help.
Father Memduh Yildirim said: “I ask the authorities to find my son. They are helping but I want more help. As parents we are burning under the sun for two days so far but there are no results.
“He was swept away here, I don’t know where he went. The searching operation continues.”
His mother, Kezban added: “Let them do whatever is needed. Let them find my child. We have four children. We ask for help from our president and premier.”
A search operation involving police, coastguard and marine search-and-rescue teams is ongoing.