An inquiry into the Ruby Princess cruise ship has identified "serious", "inexcusable" and "inexplicable" mistakes by NSW Health.
The vessel owned by Carnival Cruises visited five New Zealand ports in early March before returning to Australia.
The ship docked in Sydney on 19 March and about 2700 passengers disembarked despite signs of illness on board.
More than 600 people connected to the ship later tested positive for the Covid-19 coronavirus, and 10 died.
An Australian Special Commission of Inquiry investigated the decisions of those involved, including Carnival Australia, NSW Health and Federal Government agencies.
Commissioner Bret Walker SC handed his 315-page report to the NSW Government today and found all passengers on board should have been tested for Covid-19.
He laid bare multiple failings during the "sorry episode", taking particular aim at mistakes by NSW Health.
This included missing a "significant spike" in illness on board the ship in the days before it docked in Sydney, along with the "inexcusable" delay in testing more than a dozen swabs from the ship.
"It is inappropriate and unhelpful to make recommendations to experts that in truth amount to no more than 'do your job'," Walker wrote.
The inquiry said it had been advised of 28 deaths associated with passengers from the ship.
Twenty of the deaths occurred in Australia, with a further eight deaths reported in the United States.
The commission said 663 Australian passengers went on to contract Covid-19, together with 191 crew members.
The inquiry said the total number infected with Covid-19 may never be known due to over a third of the passengers returning overseas.
At the time, it was Australia's worst coronavirus cluster, an undesirable title it held for months until Melbourne's hotel quarantine debacle escalated.
"NSW Health should have ensured that cruise ships were aware of the change to the definition of a 'suspect case' for Covid-19 made on 10 March," the report said.
"This would have resulted in the identification of such cases on the Ruby Princess.
"NSW Health should also have ensured that such persons were isolated in cabins. These were serious mistakes," it said.
The report also said the risk rating system used by NSW Health, which saw the Ruby Princess classed as low risk, which meant no action was needed, was "inexplicable as it is unjustifiable" and "a serious mistake".
"No evidence provided to this Commission, or given by witnesses in the public hearings, comes even reasonably close to satisfactorily explaining how a decision to 'do nothing' by means of precaution was adequate, or rational," the report said.
The report also criticises a directive to allow passengers to travel interstate and internationally, against public health orders.
It then takes aim at the NSW government for not providing passengers accommodation.
NSW Premier Gladys Berejiklian said she would read the report over the weekend and comment early next week.
Eight hundred people have joined a class action against the operators of the Ruby Princess over its "misleading and deceptive" conduct surrounding the outbreak.