The Shannon based Search & Rescue helicopter was called to the scene while the Lough Derg RNLI lifeboat and the Killaloe unit of the Irish Coast Guard were also involved in the operation.
The man was pulled from the water by a local boat at around 10am.
He was then to University Hospital Limerick by Rescue 115 – the man in his 60’s was pronounced dead a short time later.
Gardaí in Nenagh are investigating the circumstances.
