Richard Cousins, 58, was CEO of FTSE 100 company Compass Group - the world's largest catering company - and died alongside Emma Bowden, 48, and her 11-year-old daughter Heather Bowden.
Mr Cousins's two sons, William Cousins, 25, and Edward Cousins, 23, were also killed.
Richard was born in Leeds in 1959 but is believed to have moved away from the area as a child, as he attended a comprehensive school in Berkshire before studying at Sheffield and Lancaster universities.
Police said the group were on holiday in Australia from the UK, and were on a return flight to Sydney's Rose Bay, close to Sydney Harbour, when the crash happened.
The plane came down off Jerusalem Bay near Cowan, 25 miles north of Sydney centre, at about 3.10pm (4.10am GMT) on Sunday.
Mr Cousins, who was recently named as one of the world's best-performing CEOs by the Harvard Business Review, was due to stand down as chief executive of Compass in March.
Paul Walsh, the firm's chairman, said: "We are 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.
"It has been a great privilege to know Richard personally and to work with him for the last few years.
"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, head of the New South Wales marine area command, told a press conference the crash "can only be described as a tragic accident".
He added: "These people had come over on holiday to one of the most beautiful parts of the world and for this to happen at a place like this is just tragic."
The sixth person who died was named as Australian pilot Gareth Morgan, 44, who worked for tour company Sydney Seaplanes.
He was said to have been an experienced pilot.
Sydney Seaplanes, which has flown passengers including singer Ed Sheeran and Pippa Middleton and her husband James Matthews, said it was "deeply shocked" by the "tragic accident".
Aaron Shaw, chief executive of the firm, which has suspended all flights until further notice, described Mr Morgan as a "gentle guy".
He added: "We are all absolutely devastated at his loss. Ringing his parents today was the one of the worst calls I've had to make in my life.
"We just want to get to the bottom of this as quickly as we can."
The single-engine plane "sunk rapidly" after hitting Hawkesbury River, the Australian Transport Safety Bureau (ATSB) said.
Police divers were flown to the scene, and all six bodies were recovered on Sunday evening.
It may take several days to recover the wreckage of the plane.
The ATSB said: "At around 3pm, a DHC-2 Beaver Seaplane, VH-NOO, operated by Sydney Seaplanes was flying in the vicinity of Jerusalem Bay (near Cottage Point).
"It is understood that there was one pilot and five passengers on the aircraft on a return flight to Rose Bay, Sydney Harbour.
"The sequence of events leading up to the accident are not yet understood, however following the impact with the water, the aircraft is reported to have sunk rapidly."
About 10 recreational boats were believed to be in the area at the time of the incident, and police have appealed for anyone who may have seen what happened to come forward.
An investigation has been launched to establish the circumstances leading up to the crash.