Five people were killed in the early hours of Thursday morning when their overcrowded boat collided with a fishing vessel.
Four young women and a man were killed at the scene, and nine other people were injured, one critically.
The small boat was carrying 14 people when it was only designed to accommodate eight, Marine Area Command Police Inspector Glenn Finniss told reporters. However, he would not speculate on the cause of the accident.
It appears to have been an unauthorised social outing about the 23ft half-cabin cruiser.
Sydney Ship Repair and Engineering, the boat's owner said that the craft was missing when they turned up for work and was not on an authorised trip. The boat is used to ferry staff to work on an island.
"All my staff have been accounted for," general manager John McPherson told the Daily Telegraph online. "None of them work overnight."
Finniss said that the crew of two on the trawler escaped injury and made emergency calls as other boats also came to the rescue.
He also said that factors including speed, whether navigational lights were used and overcrowding of the boat would all be part of the investigation.
