A Sydney swimming coach used his workplace as a sexual playground to brazenly abuse 11 young students, a jury has been told.
"There is almost nowhere at the (Sydney) swimming pool that the accused didn't commit sexual offences," prosecutor Darren Robinson said on Friday in the NSW District Court.
He was giving the crown closing address at the trial of Paul Douglas Frost who's accused of sexual offences against 10 boys and one girl between 1996 and 2009.
The 46-year-old has pleaded not guilty to more than 40 charges.
They include having sexual intercourse with a child, indecently assaulting a child, enticing a child to commit an act of indecency and exposing a child to indecent material.
Mr Robinson said each of the 11 complainants told the truth when they testified to being sexually abused by Robinson.
"Their evidence was compelling," he said.
"The suggestion that each of the complainants has fabricated their evidence is so implausible it offends common sense."
Nor had any of the 11 concocted their evidence.
Most of them had not talked to each other since they left the swim school years ago and they told the jury they understood their evidence was not to be shared.
He said the evidence revealed Frost groomed the boys, first discussing masturbation and other sexually explicit topics and answering any sexual questions they felt they couldn't ask their parents.
He normalised sexual behaviour, following a "playbook" when he progressed from discussing sexual topics, to encouraging masturbation and then taking part in sexual activities.
Evidence from a trainee teacher who kept a diary when she was at the school for only a few days in 2002 provided a real insight into the culture.
"Paul is a bit strange in the way he acts around the kids," she wrote.
He admitted having children sit on his lap, a practice described as inappropriate in evidence given by a registered coach.
"This was not innocent behaviour but calculated to test the boundaries," the prosecutor said.
Frost had operated in a brazen way, including by encouraging one boy to masturbate on the pool deck under the cover of a towel.
Because it was very brazen didn't mean it didn't happen, but showed he was following the playbook.
"The Crown says don't fall into the trap of thinking there was so much activity happening at the pool that there was simply no opportunity," he said.
"He created the opportunity on a daily basis in many different ways."
There was nobody behind the reception area for long periods and there were two doors he could hear opening before anyone would walk into the male changing room.
The prosecutor alleged Frost committed sexual offences in a lot of places at the pool complex, telling the jury the centre was "his sexual playground".
"There is an overwhelming amount of evidence that points in the one direction - the guilt of the accused," he said.
The trial continues before Judge Michael King.
