A widescale marine search is underway for a Coodanup man and his family that did not return home from a fishing trip on Thursday.
The Water Police Coordination Centre in Fremantle is leading the search, with support from three helicopters, nine vessels and an AMSA plane.
Police have confirmed the men missing are a 50-year-old Coodanup boat owner, his brother, his 24-year-old son and a family friend.
The alarm was raised at 9pm on Thursday after the quartet did not return home from a fishing trip.
The 5.5m vessel is believed to have left Cockburn Sound on Wednesday evening, with the men planning to go fishing at Rottnest Island.
Water Police, Volunteer Sea Rescue groups, Rottnest Rangers and local Police have conducted overnight searches for the vessel without success.
The Mandurah Volunteer Marine Rescue Group confirmed they are helping to locate the missing men.
No emergency calls have yet been received from any of the occupants on board.
Anyone with information should contact Water Police on 9442 8600.