Valentia Coastguard says a hoax call has cost emergency services tens of thousands of euro.
The bogus call was made on Sunday morning.
Around 25 past 9 a call was made to Valentia Coastguard from a man claiming he was on board a yacht around a mile off Roche’s Point in Cork, which was taking on water.
The man claimed he was up to his waist in water and required immediate help.
Valentia Coastguard tasked Ballycotton and Crosshaven lifeboats and Crosshaven Coastguard Unit to the scene.
The Shannon Coastguard Helicopter was also deployed and the Waterford Coastguard Helicopter, which was close by on a training excerise, was diverted to the search.
Members of the Royal Yacht Club who were on the water at the time said they had not seen the vessel nor heard any mayday calls over the radio.
Valentia Coastguard say they are satisfied that the incident was a terrible hoax, which cost the emergency services tens of thousands of euro.