One man died and two others were rescued suffering from shock and hypothermia yesterday after jumping into the sea off rocks.
It is understood the three people, all from Ballymoney, had been "rock jumping" when they got into trouble in heavy seas near Dunluce Castle on the north Antrim coast.
An air and sea rescue operation was mounted involving the Coastguard, Royal Navy and lifeboats from Ballycastle and Portrush following a distress call from a teenage girl who was reported to be with the group and saw the three men carried out to sea.
All of the men were taken from the sea by a lifeboat crew, but one later died in hospital.
Mr John Hope of the Coastguard said: "The boys had been diving into the sea but there were 12 to 15 foot swells in the area and they were swept out. A teenage girl, who was with them, raised the alarm and sparked the operation.
"The sea is very treacherous. Even in a boat around the rocks, it's dangerous. So to be jumping into the sea from rocks is not something I would advise people to do."
The three men were pulled out of the water by a lifeboat crew and the girl was air-lifted to safety. All four were taken to the Causeway hospital in Coleraine, Co Derry, where they were reported to be suffering from various degrees of hypothermia and shock.
In Co Down, four people were rescued from the sea by helicopter after their motor boat capsized off Ardglass.
The incident was spotted by golfers on the local course who made an emergency call.
Meanwhile, the police released the name of a Lithuanian man whose body was pulled out of a river in Co Tyrone.
Mr Zigmas Vilinas (38) had been living in Coalisland, Co Tyrone, where his body was discovered on Saturday in the Torrens river in the town. A woman walking her dog along Dungannon Road spotted the body near a bridge. Police do not suspect a crime.