A man and three children have been treated by paramedics after facing difficulties in the sea at Castlerock, County Londonderry.
They were using body boards on Saturday when they got caught in a rip current for up to 20 minutes.
The alarm was raised once a member of the public spotted them waving their arms.
All four people got themselves to shore just before the Coleraine Coastguard rescue team arrived.
None of those involved sustained any serious injuries but they were treated by the ambulance service for shock, coldness and taking in sea water.
Chris Little from Coleraine Coastguard said the incident could have been "very serious".
"People need to be careful at this time of year," Mr Little told BBC News NI.
"These people were visiting Castlerock and they certainly weren't expecting this to happen."
Mr Little said it can be very difficult to get back to shore when caught in a rip current.
"We responded straight away but they did a lot of hard work themselves," Mr Little said.
The incident unfolded shortly after the annual Portrush Raft Race ended, he added.
"An inshore lifeboat was also sent but everything was stood down pretty quickly once we knew they were being looked after by paramedics."