Old debris and local reefs are making the search for the fuselage of a light plane that crashed off Victoria's surf coast difficult.
Police believe one of the four people killed when the Piper Cherokee plane that plunged into the sea on Friday is still trapped in the wreckage.
The other three bodies were recovered within hours and most of the plane's debris has washed ashore, but police say the search for the fuselage is proving hard, even with sonar technology.
Weekend efforts focused on Bass Strait off Point Lonsdale.
Inspector Graham Banks of Geelong police said the wreckage was thought to be about 30 metres under water in a 500m by 500m search area that could be expanded.
Police have not named the victims but it's believed they are Daniel Flinn, 55, Donald Hateley, 68, and Ian Chamberlain and his partner Dianne Bradley, both in their 60s.
The three men are all licensed private pilots, but it's not clear who was flying the plane.
All four were reportedly keen members of the flying community.
Tom Flinn told The Age his brother Daniel was an avid pilot "and that was his passion".
The plane was flying from Moorabbin Airport in Melbourne to King Island in Tasmania.
Emergency crews were alerted about 12.30pm on Friday after a fisherman out at sea noticed the aircraft was in trouble and crashed into the water.
