Four teenagers were rescued from the water off the Co Down coast on Saturday night, officials say.
They were trapped by the tide, up to their shoulders in water, while walking from Ballykinler to Dundrum.
A former coastguard who lives nearby put his dinghy into the water and reached the teenagers, who were showing signs of hypothermia and complaining of the cold.
Gary Young, watch manager at Belfast Coastguard, said: "These teenagers are extremely lucky to have been rescued.
"I would like to pay tribute to the quick thinking of a former coastguard whose actions certainly made for a happy ending to this potentially life-threatening incident."
"We would like to remind anyone visiting the coast to take great care near water."