Daniel Kelly said he would never be able to rest until his five-year-old son Chayce Kofe had been recovered from the sea that snatched him off the central coast beach in a flash last week.

"The last time I saw him, he was driving away in a car waving goodbye daddy and now I'll never get to see my beautiful son again," he said.

"I just need to find him, I need to get him back. I can’t leave him out there; that’s like leaving one of your kids in a different country and not going back to get him but knowing you can never see him again. It’s just wrong. I just want to get him back."

Chayce was playing on the shoreline on Thursday afternoon when a wave swept him out to sea just metres from a holiday house his aunt was renting.

He was seen again for a brief moment, metres out to sea, but none of the cousins or siblings with him were competent swimmers, police said.

A large-scale air and sea search since Thursday has failed to find Chayce.

On Monday, a police spokeswoman said local water police would do intermittent sweeps of the area but the full-scale search had ended.

Mr Kelly has called for better signage at the beach, which is not patrolled and has a reputation for dangerous conditions.

"If they don’t put more signs up, I’ll make some and put them up myself," he said. "No one should swim up there, no one should even go up there and play, it’s so dangerous up there especially [for] kids. It should be closed off to kids."

Resident Anthony Learmonth, who did a thesis on the beach morphology of Pearl Beach, said it was one of the most deceptively dangerous beaches in the state.

The beach has extremely coarse sand, unlike any other beach near Sydney, and as a result, waves do not break offshore and roll in gradually. They break directly on to the beach face itself.

On the day Chayce went missing, violent waves were breaking on the shoreline "like cannons going off", Mr Learmonth said. But in between sets, the bay-like spot looks deceptively calm, he said.

"My partner wouldn't let her kids go in the water at Pearl Beach when they were smaller because it's just too dangerous. Locals know it but it's a big holiday house destination; a lot of people rent out houses there and they don't know the risks."

A Gosford City Council spokesman said the unpatrolled beach was Crown land so any signage was the state government's responsibility. The Department of Primary Industries has been contacted for comment.

Chayce's father described his eldest son as a cheeky, adventurous boy who had started kindergarten at Umina Beach this year. He loved riding his bike and watching movies, Mr Kelly said.

"[He was] just a cheeky little boy," he said. "Every time I went to the toilet, he’d go to the toilet. Every time I got up and put my shoes on he was getting up and putting his shoes on. Everywhere I went, he went.

"I’ll never give up trying to bring my son back into my arms. I miss my Chayce boy so much."