A man has been rescued but police have "serious concerns" for three people after they failed to return from a far north Queensland fishing trip.
The 36-year-old Tongan national is believed to have been in the water for about 30 hours before being spotted clinging to a buoy off the Queensland coast by an aerial search.
He is currently being treated for hypothermia and exposure in Innisfail Hospital.
A "significant" search continues for another three men who were on what was supposed to be an overnight fishing trip with the 36-year-old.
The four men had set off from Mission Beach on Friday.
"We will continue with our search...and make another decision ...tomorrow," Acting Inspector Brett Jenkins told reporters.
"If they are still in the water we do hold serious concerns for their welfare."
Emergency services launched an aerial, water and land search early on Sunday morning when notified by the men's family they had not returned.
The missing men are a 24-year-old "local" who owns the boat and two Vanuatu nationals, aged 26 and 31.
Police believe their boat experienced engine trouble when returning on Saturday before taking in water and sinking quickly near the Barnard Island Group National Park north of Mission Beach.
After failing to activate the boat's EPIRB, the men are believed to have attempted to swim to an island, Acting Insp Jenkins said.
The 36-year-old was found at about 4.30pm on Sunday by a helicopter search and rescued by nearby water police.
He provided information on where the boat sank, helping pinpoint the search, Acting Insp Jenkins said.
"We are still concentrating our search on the ... coastline in the event that any of the missing persons have made it to shore," he said.
