Searches for two men who went missing off the Queensland coast in separate incidents have failed to find either man today.
An extensive air and sea search for a missing Japanese kayaker off Fitzroy Island in the state's far north has so far been unsuccessful.
The 29-year-old employee of the Fitzroy Island Resort went missing yesterday afternoon while kayaking with a colleague.
Searchers found his kayak near Port Douglas this morning.
Sergeant Andrew Ibell from Cairns Water Police says there are grave concerns for the man.
"Probably the biggest thing is just the actual sea surface conditions," he said.
"Rough choppy seas at the moment, fairly strong tides which will make surviving on the surface very difficult unaided without any flotation."
Meanwhile, police continued searching until last light this afternoon for a man who has been missing off the Mackay coast since the weekend.
The 35-year-old disappeared on Saturday afternoon.
Police say he was diving for sea cucumbers.
A large-scale search involving up to nine aircraft has so far failed to find any sign of the man.
A decision on whether to resume the search is expected to be made in the morning.
Kay Becker from the Capricorn Rescue Service says hopes are fading that the man will be found.
"There's so many little islands and quays out there in that area that we lived in hope that he'd been able to make it to one of of those," she said.
"But they concentrated their search very heavily on that area there today and nothing was seen, so very unfortunate.
"You know a long way out to sea, so there would have been lots of variables that he would have been up against."
Ms Becker says an unknown item spotted around lunchtime is not linked to the missing man.
"It's very easy for there to be lots of stuff out there - they were quite a long way out and you know there would be stuff off boats around all the time," she said.
"But they have absolutely confirmed that it's nothing to do with this search."