A high-profile British businessman and his family have been identified as the passengers killed when their seaplane crashed into the Hawkesbury River north of Sydney.
Experienced Australian pilot Garath Morgan, 44, died when his aircraft plunged into Jerusalem Bay, along with businessman Richard Cousins, 58.
His sons, Edward and William Cousins, aged 23 and 25, also perished in the flight, as did his fiance Emma Bowden, 48, and her daughter, Heather Bowden-Page, 11.
Richard Cousins was identified by police as the CEO of the world's largest food catering company - Compass Group.
Australian pilot Gareth Morgan, 44, inset, was among the six people killed in the seaplane crash. Source: AAP, Facebook
Mr Cousins in September announced his retirement from the company after turning around it's financial misfortunes throughout his 11-year tenure, UK media widely reported.
He was named as the world's 11th most powerful CEOs by the Harvard Business Review this year.
Paul Walsh, Compass Group chairman, said the company was "deeply shocked and saddened by this terrible news".
"The thoughts of everyone at Compass are with Richard's family and friends, and we extend our deepest sympathies to them," he said.
"Richard was known and respected for his great humanity and a no-nonsense style that transformed Compass into one of Britain's leading companies."
Detective Superintendent Mark Hutchings from the NSW Police Marine Area Command said authorities have been in contact with the United Kingdom but formal identification by the coroner is still ongoing.
The plane has not yet been recovered from the crash site at Cowan.
Prime Minister Malcolm Turnbull earlier offered his condolences to the families of those killed in the crash.
"It is a tragic accident and ... our hearts go out to the families of those whose lives were lost," Mr Turnbull told reporters in Bondi on Monday.
"We don't know yet what caused it, but it's just a tragedy. We grieve for those who lost their lives."
Police are now working on the logistics of refloating the wreckage.
The plane will need to be brought back to the surface before forensic air-crash investigators can piece together what went wrong.
The Australian Transport Safety Bureau is investigating the incident.
Sydney Seaplanes, which has been operating for 80 years, provides flights above and around some of the city's most popular tourist sites including the Opera House, the Harbour Bridge, Pittwater and the Hawkesbury River region.
The plane was believed to have been travelling from the picturesque Cottage Point Inn to Rose Bay.
