Up to 30 knot winds and 1.5m swells have proved difficult for rescue crews, with police confirming the search is scheduled to resume on Wednesday morning.
Emergency services were called to Little Bay Beach in Arakoon on the NSW mid-north coast following reports an 18-year-old man was in trouble in the water.
Police alongside Marine Area Command officers and Surf Life Saving NSW responded and conducted a search of the area, but were unable to locate the man.
The search was called off after an extensive sweep on Monday and resumed at 8am on Tuesday, with crews planning to return the water on Wednesday.
The missing man had recently completed his Year 12 exams at the King's School in Sydney's west, acting principal Stephen Edwards confirmed in a statement.
"The school is in contact with the family and will continue to provide support, while respecting their request for privacy," Mr Edwards said.
"As the search continues, I ask that you keep the family in your prayers and hold them in your hearts."
John Murray, from volunteer group Marine Rescue NSW, said vessels from Trial Bay and Port Macquarie searched waters from Laggers Point to Gap Beach for almost eight hours.
On Tuesday, the winds and swells put the volunteer crew out of action after a few hours.
"It has become quite uncomfortable, making it extremely challenging for our volunteers," he said.
It is the second incident in the region in recent days after a 59-year-old died on Friday after being pulled from the water in Crescent Head.
In November, a shark attack killed a Swiss woman and severely injured a Swiss man both swimming at a remote beach also on the NSW mid-north coast.
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