The family of a teenager feared drowned off a central coast beach have spoken of his "heartbroken" twin, as emergency services resume their search for the boy as well as a rock fisherman missing off the far south coast.

Keon Sbrugnera, 15, was swimming with two friends and his girlfriend at The Entrance about 3.30pm on Sunday when they got caught in a rip. They all made made it back to shore, except for Keon.

"The family is really not holding up well at all," the teenager's grandmother, Joan, told The Newcastle Herald.

"It's just terrible. Callan [his twin] is just heartbroken; the whole family is."

Callan Sbrugnera and Keon's Wyong High schoolmates gathered at the central coast beach yesterday in the hope he would be found alive.

On Facebook, Keon's friends set up the pages "Stay Strong Keon Sbrugnera" and "Keon Sbrugnera, you will always be my hero", writing "please come home" and "hang on".

"Miss you bubba, wish you were still here," another friend wrote.

On the NSW far south coast, a 56-year-old Canberra man was fishing off the rocks about 300 metres west of Haycock Point in Eden about 8.30am yesterday when he was believed to have fallen into the water or been swept away, police said.

Another rock fisherman in the area saw his equipment on the rocks about 2.30pm and called the police.

It was not known when the man entered the water, Westpac Life Saver Rescue Helicopters' chief executive Stephen Leahy said this morning.

The man's car was found at a nearby car park and a search involving the police's Marine Area Command, Merimbula Marine Rescue and Pambula Surf Life Saving Club was launched.

The rescuers battled 2.5-metre waves, but the man was not found.

Mr Leahy said boats from Marine Rescue NSW and NSW Maritime, as well as a Westpac Life Saver helicopter, were helping with the search today.

The weather conditions were reasonable, he said, adding: "There are lots of rocks in the area but the ocean itself is reasonably calm and there are light winds in the area.