Emergency crews were called to Wattamolla in Sydney's south at 11am on Sunday after reports of two people being dragged into the ocean as rough conditions continue to batter the east coast.
The pair was winched from the ocean with the aid of PolAir but the man was unable to be revived and died at the scene.
He is yet to be formally identified and a report is being prepared for the coroner
The teenager was taken to the Children's Hospital at Randwick where he remains in a stable condition.
The latest drowning comes after a spate of deaths, including two fisherman on the NSW south coast on Friday and Saturday and another in Sydney's north.
The Bureau of Meteorology has cautioned residents to take extra care, with hazardous surf conditions across the NSW coast.
Royal Life Saving Australia CEO Justin Scarr said past investigations had prompted strong advice for rock fishers to wear life jackets and safety equipment but most importantly check weather conditions.
"What we've had is significant swell that has meant almost no rock shelf between the Queensland border and Melbourne is safe for rock fishing," he told AAP on Saturday before the most recent tragic drowning.
Dr Scarr said people heading to waterways on Sunday and Monday should think twice about rock fishing and check the weather warnings, particularly wave action and direction.
He urged parents to constantly watch children around water and said boaties needed to have enough life jackets aboard.
Over the past 20 years, 118 people have drowned during Easter, according to Royal Lifesaving Australia.
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