The men, in their 40s and 60s, got into difficulty in separate incidents in the swimming section of the race.
Two men have died at an Ironman competition in Ireland.
The men, in their 40s and 60s, got into difficulty in separate incidents during the swimming leg of the race in Youghal, Co. Cork this morning.
They were removed from the water by emergency services but pronounced dead at the scene.
Irish police said they are investigating and the coroner has been notified.
The event had been postponed from Saturday due to flooding and bad course conditions after Storm Betty.
It consisted of a 1.9km swim in Youghal Bay, a 90km bike course and a 21.1km run.
The swim had already been cut from 3.8km due to poor weather conditions.
The race continued and competitors were allowed to finish despite the double tragedy in the first section of the race.
In a statement, the event organisers said: “We are deeply saddened to confirm the death of two race participants at the Ironman 70.3 Ireland, Cork 2023.
“During the swim portion of Sunday’s race, safety personnel provided immediate medical attention upon recognising the athletes were in need of assistance.
“We share our greatest sympathies with the families and friends of the athletes and will continue to offer them our support as they go through this very difficult time.
“We thank the safety personnel and first responders who worked quickly to provide the athletes with medical assistance.