Rescue crews were alerted to the incident at 4.55pm, NSRI spokesperson Craig Lambinon said.
He said the City of Cape Town (CoCT) water rescue network was alerted to reports from CoCT lifeguards and Fish Hoek Lifesaving lifeguards performing cardiopulmonary resuscitation (CPR) efforts on a local 15-year-old boy.
Lambinon said the teenager was rescued from Fish Hoek Beach.
“The teenager had reportedly dived off rocks into the surf before being rescued from the water by the lifeguards.
“The South African Police Services (SAPS), Western Cape Government Health Emergency Medical Services (EMS), Cape Medical Response(CMR) and CoCT Law Enforcement responded,” Lambinon said.
He said crew members from the NSRI Simonstown were placed on alert.
“On arrival on the scene, paramedics assisted the lifeguards with CPR efforts.
“After extensive CPR efforts were exhausted sadly the teenager was declared deceased.
“The body of the teenager was taken into the care of Government Health Forensic Pathology Services. Condolences are conveyed to the family of the deceased teenager,” Lambinon said.
Police have opened an inquest docket.
In an unrelated incident, a Uitenhage man on holiday with his family in Mossel Bay in the Western Cape was commended for his heroism after he rescued a teenager.
Charles van Wyk was watching over his 12-year-old son at Die Poort Tidal Pool when he noticed two young females appear to grow tired while swimming, and one of them appeared to be in distress, the Mossel Bay Advertiser reported.
Another woman tried assisting the girls but retreated. Van Wyk launched into the water and swam past his son, reaching the two young women, and helping a 15-year-old to stay afloat. He was able to bring the teenager closer to shore where he was assisted by an unidentified man. Together they brought the teenager to shore, while the second girl managed to reach the shore unassisted.