The man was brought from the water by surfers near West Strand who have been praised for their swift action.
Having seen the man in difficulty in the water, they pulled him to shore on a surfboard, carrying out CPR as they did so.
Both Portrush RNLI’s inshore and all-weather lifeboats were launched following a report from Belfast Coastguard shortly after 8pm that a person was in difficulty in the water near Blackrock.
"The casualty was assisted to shore by surfers. The inshore lifeboat crew assisted the surfers with casualty care while the all-weather lifeboat stood by,” said a spokesperson for Portrush RNLI. The casualty was subsequently handed into the care of an ambulance crew on arrival and transferred to hospital.
"Well done to the members of the public who responded so professionally to the incident.
"Unfortunately it has since been confirmed that despite the best efforts of everyone involved, the man has passed away.
“Everyone at Portrush Lifeboat sends sincere condolences to the man’s family and friends.”
Sympathy has also been extended by East Derry SDLP MLA Cara Hunter.
"This is a tragic loss of life and my thoughts are very much with this man’s family at this incredibly difficult time. I cannot imagine how difficult it must be to lose a loved one in such circumstances.
"I would also like to pay tribute to the two members of the public who entered the water and brought the man back to shore and all the emergency services who responded to this incident."
Independent East Londonderry MLA Claire Sugden described the tragedy as “absolutely heartbreaking news”.
"My thoughts and prayers are with this man’s family and friends. I would also like to praise everyone who helped in this rescue attempt,” she said.