According to the Irish Independent, paramedics tried to revive the 69-year-old man without success after he was pulled out of the water by a lifeboat just before 4pm on Saturday.
He was described as a holidaymaker, in Portugal with family and friends, and had gone into the sea for a swim.
The tragedy occurred at Peneco Beach, one of Albufeira’s two main beaches, near the city’s marina.
Portimão Port Captain Santos Pereira said authorities received a call at 3.43pm that a man was floating in the sea.
He said that despite attempts to resuscitate the Irishman, he was declared dead at the scene.
In related news, another man also drowned on Sunday afternoon on Albandeira beach in Lagoa.
According to reports the circumstances leading up to the death were being investigated.
The alarm was raised at around 3pm and Maritime police, local fire-fighters and INEM emergency medics rushed to the scene.
At this time of year there are no lifeguards on Albandeira beach and on the day in question the water was rough with waves of up to three metres.