The man, aged in his 50s, was swimming near a river mouth at Urunga, 2km from the closest surf lifesavers when they got into trouble at 11.30am.

Police called the lifesaver to help when two people were reported treading water at the mouth of the river.

An inflatable rescue boat was able to retrieve a man and bring him to shore, however CPR efforts were unsuccessful and he was declared deceased by paramedics.

The child managed to get back to shore unassisted.

Urunga Patrol Captain Garry Howe was the IRB driver and said when they got to the river mouth, there was a crowd on the beach pointing to where the man was floating.

He was unconscious and they pulled him into the IRB and commenced CPR. They landed the IRB and police assisted with CPR until the Ambulance arrived.

Two patrol members drove the 4WD vehicle up the beach to assist the 14-year old boy who had made his own way to shore.

Garry Howe said that people walk along the boardwalk and jump in at the unpatrolled beach at the end.

"It's a really nice looking beach, but very dangerous. There are always people swimming there on a nice day."

He praised his team of lifesavers, saying everyone performed very professionally. "We all worked together and you can't ask for anything more than that."

Surf Life Saving NSW CEO Steven Pearce is urging people to take extra care for the remainder of the long weekend and school holidays.

"We are doing all we can to protect the public and holidaymakers across the state. Please swim at patrolled beaches only and be aware of the conditions and your own abilities if you are out and about on the water," he said.