SURF expert Robbie Sherwell has warned of increased dangers for Coast swimmers following the death of a man at Yaroomba Beach.
Mr Sherwell said strong currents and unstable sandbanks meant swimmers could be swept away at any moment and warned against entering the water unless lifeguards were present.
"People can think they're safe because they can touch the bottom but all they've got to do is move that extra foot and the sandbank will just fall away and they get carried off into a rip," Mr Sherwell said.
He said conditions had been highly dangerous in the last month because drastic wind changes had produced deeper gutters close to shore.
"The sandbanks have been super unstable," he said.
"We've had a lot of really deep gutters.
"The currents are moving back and forward so off the edge of a sandbank it just seems to disappear, just drop away."
Mr Sherwell's warning follows the death of a man who became caught in a rip while swimming at Yaroomba Beach on Saturday night.
Police said the 36-year-old Yaroomba man was pulled from the surf at about 6.30pm but died at the scene after witnesses and paramedics tried to resuscitate him for about an hour.
Swimmers at the beach noticed the man in trouble in the rip, but when they swam out he was facedown in the water, according to police.
A surfer brought the man to shore on his board and several people tried CPR until paramedics arrived.
Surf Life Saving Queensland's Sunshine Coast lifesaving services coordinator Tasman McClintock said no one was patrolling the beach because the incident occurred after hours.
Mr Sherwell, a former professional surfer whose XL Surfing Academy has operated on the Coast for more than 15 years, advised against swimming without lifeguards present.
"Tragedies occur on unpatrolled beaches, particularly after the lifeguards are off duty," Mr Sherwell said.