Police and the authorities on the Greek island of Zakynthos have begun an investigation into the death of former Eastbourne College student Harry Byatt.
Nineteen-year-old Harry, who left the college last year, died during a snorkelling and diving accident in the early afternoon of August 6.
His body was discovered on the seabed at a depth of about 30 metres, according to reports from the island.
The popular teenager, whose mother Alexandra was a childhood friend of Princess Diana and served as her lady-in-waiting in the 1990s, had been working as a water sports instructor at the luxury Peligoni Club in the Greek island holiday resort.
A club spokesperson said the alarm was raised five minutes after Harry dived under the water using a monofin and a mask.
He was found unconscious, brought to the surface and CPR was administered on a rescue boat.
Once ashore, three doctors, two guests from the UK and one local doctor, and an army medic from the UK did everything they could to revive him on site while awaiting the ambulance, said the spokesperson.
He was rushed to hospital but pronounced dead.
Harry was described as a “beloved son, brother and friend” on his memorial Facebook page.
A statement from the college said the school community was “deeply saddened” by his death.
“Our thoughts are with his family at this incredibly sad time,” said a college spokesperson.
“The college and CCF (Combined Cadet Force) flags will fly at half-mast at the beginning of next term.”
The spokesman for the Peligoni Club, which is working with authorities to investigate the incident, said, “At this time our thoughts and prayers are with his family, friends and colleagues.”
A Foreign Office spokesman said, “We are supporting the family of a British man who died in Zakynthos, Greece, and are in contact with the local authorities.”
Friends have described Harry, who had been studying at Oxford Brookes, as a “beautiful soul, always smiling, always a gentleman” who was unique and special.
No funeral details have been released and no further information has been released by the authorities.
Mrs Byatt is the daughter of Sir Julian St John Loyd, who served as land agent to The Queen at Sandringham up until 1991.
Harry’s father Duncan Byatt, 55 – now a senior civil servant at the Cabinet Office – had been the chief executive at The Foundation of Prince William and Prince Harry.