It is believed the vandals boarded five vessels causing damage to at least three.

According to one boat owner, Helen Hall, the vandals also stole several items from her boat with the damages expected to cost around $20,000.

“They’ve broken in through the en suite, taken knives and slashed through the tender and tried to remove an LCD television.

“Then they threw all of the crockery overboard, damaged the electronics and have stolen knives, wetsuits, a hand held radio and two rare Riviera towels.”

“The damage could have easily been much worse - there are leather lounges on the boat and they could have easily taken the knives to them as well.”

Mrs Hall said she never thought there would be a problem with vandals or thieves because there were bolted security gates and barbed wire at the entrance to the marina.

“It looks like they’ve taken a smaller boat form the yacht club and come across on that.

Detective Senior Constable Brad Richards-Scully agreed that was one of the possibilities.

“There is evidence that the offenders were wearing shoes when they boarded the boats and it is difficult to see them swimming over in shoes.

“So it is a possibility that they have boarded from another boat or climbed around the security gates at the entrance to the marina.”

Several other boats were boarded with the vandals spraying sun cream over the stern deck and breaking the locks off the doors of the galley on another.

On the same night Mackenzies tug boat, the Cape Le Grand II, was also boarded and suffered minor damage.

According to Det Sen Constable Richards-Scully there were also items stolen from that vessel.

“They’ve let the fire extinguishers off and there was foam everywhere.

“Police recovered the stolen items on the yacht club beach and they were returned to Mackenzies Island Cruises.”

Police hope that forensic evidence found on the Cape Le Grand II will aid them in identifying those who were involved.

“We are still calling on members of the public to help the investigation by coming forward with any information they may have in regards to the identity of people involved or the location of any stolen goods,” Det Sen Constable Richards-Scully said.

Anyone with information should contact police on 9071 1900 or Crimestoppers 1800 333 000.