A woman has been found dead after being thrown overboard in a boating accident.

Emergency services were called to a stretch of water known as the Marion Narrows at Marion Bay in Tasmania‘s southeast about 11.45am on Wednesday following reports of a boating incident.

Three of four passengers in a 4.5-metre fibreglass runabout were thrown into the water after it likely became caught in the choppy wake of a passing vessel.

Conditions on the water had been calm and onlookers on a nearby vessel rushed to their aid but were only able to locate and retrieve two men.

A woman, believed to be in her 70s, was not found, sparking a major police search and authorities confirmed her body had been found on Wednesday evening.

Initial reports suggested the boat had capsized, but police now believe it simply veered to its side in the wake of a passing vessel.

‘We now know that the boat appears to have either hit a wave or some chop from another boat and that has potentially caused their boat to veer to one side, which has then caused the three people to be thrown into the water,’ Southern District Commander Jason Elmer said.

‘This appears to have been a freak accident.’

Three out of four people on a boat in Marion Bay (above), in Tasmania's southeast, were thrown into the water on Wednesday morning
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Three out of four people on a boat in Marion Bay (above), in Tasmania’s southeast, were thrown into the water on Wednesday morning

A woman, believed to be in her 70s, died in what southern district commander Jason Elmer (above) labelled a 'freak accident'
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A woman, believed to be in her 70s, died in what southern district commander Jason Elmer (above) labelled a ‘freak accident’

All three passengers were believed to have been wearing personal flotation devices.

‘A nearby vessel has come to the aid of the persons in the water and two males were taken from the water,’ Commander Elmer said.

The elderly woman’s body was discovered later.

‘This is a tragic outcome, and our thoughts and condolences go to their family,’ Commander Elmer said.

‘We also wish to thank those members of the public who came to assist.’