A bodyboarder has died after being pulled from the water on Sydney's northern beaches while taking part in a competition.

Mauricio Abrunhosa, 48, was competing at Curl Curl beach this morning when a fellow rider spotted him in trouble.

He was pulled from the surf unconscious, and an off-duty nurse did CPR until NSW Ambulance paramedics arrived.

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He was rushed to Royal North Shore Hospital but later died.

Known as Moz, Abrunhosa was a member of the Sydney Bodyboard Club and was a two time state champion in the sport.

Surf Life Saving duty officer Tracey Hare-Boyd said life savers didn't know what happened.

We are unsure if the bodyboarder actually fell ogf his board and hit his head or of it was a medical episode," she said.

Friends are paying tribute to Abrunhosa.

"I think the whole community feels quite deep and sad because it could be any of us I guess," one friend said.

NSW Police said a report would be prepared for the information of the coroner.