A police search for a 32-year-old swimmer who failed to resurface in a Sydney river has resumed.
The man was on a houseboat with family and friends on the Hawkesbury River at Laughtondale, near Wisemans Ferry, when he went for a swim nearby about 6pm on Monday.
He never resurfaced.
Locals, police, the SES and a rescue helicopter mounted an extensive search of the area before poor light halted progress about 10pm.
The search resumed about 8am on Tuesday, with police divers now involved.