Both Wicklow RNLI lifeboats launched at 1.40pm today after a small boat with four occupants sank eight miles north east of Wicklow harbour.
The 17ft motor boat with two adults and two young children began to take water when the skipper managed to radio a distress call before the boat sank.
The family spent a short time in the water before a nearby fishing vessel picked them up.
The trawler was asked to proceed back towards Wicklow to meet the lifeboat.
The inshore lifeboat was alongside the fishing vessel 20 minutes after launching.
Two lifeboat crew were put on board the fishing vessel to access the casualties, who were then transferred to the all-weather lifeboat, as they were showing signs of hypothermia and shock.
An ambulance was requested to meet the lifeboat on arrival.
The lifeboat landed two adults and two young children at the South Quay after 2.30pm, where they were met by an ambulance crew.
They were checked out and later released unharmed by their ordeal.
Speaking after the callout lifeboat operations manager Des Davitt said: "The boat sank very quickly and the four people were adrift in the water.
"If it was not for the swift action by the crew of the fishing vessel, this might have had a more serious outcome."