NSW Police have confirmed the bodies of six people have been recovered and brought back to land after a seaplane crashed into Jerusalem Bay near the town of Cowan, north of Sydney on Sunday afternoon.

Key points: One pilot and five passengers were on board the seaplane

One pilot and five passengers were on board the seaplane Parts of the wreckage have been found

Parts of the wreckage have been found Plane was returning group from Cottage Point restaurant to Rose Bay

All five passengers and the pilot of the seaplane died when it crashed into the water in Hawkesbury River about 3:15pm.

Police divers have recovered the bodies from the submerged wreckage.

Aaron Shaw, the company's managing director, confirmed one pilot and five passengers were on board.

The seaplane was returning a party of five people from the Cottage Point Inn Restaurant to Rose Bay in Sydney's east when it crashed into the water.

Sorry, this video has expired Search for survivors after seaplane crashes into Hawkesbury River

The journey from Cottage Point to Rose Bay would normally take 20 minutes.

Numerous rescue vessels, including NSW Police divers and NSW Ambulance helicopters, attended the scene.

Some debris has been retrieved but the plane remains 13 metres below water.

The DHC-2 Beaver was operated by Sydney Seaplanes. ( Supplied: Sydney Seaplanes )

The crashed aircraft, a DHC-2 Beaver registration VH-NOO, was operated by Sydney Seaplanes.

A marine command centre has been established at Apple Tree Bay boat ramp near Bobbin Head in the Ku Ring Gai National Park, near Cowan.

Police will guard the wreckage overnight until investigators from the Australia Transport Safety Bureau arrive at the scene on Monday morning.

Police are urging anyone who witnessed the accident to contact them.

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In a separate incident on the Hawksbury River, a 29-year-old woman was taken to hospital after falling off a wakeboard and being struck by another boat on Sunday.

Police said she was helped from the water by onlookers just before 6:00pm, and treated by paramedics for back and hip injuries.

She was flown by the Careflight rescue helicopter to Westmead hospital in a serious but stable condition.