Australia wants an expanded fleet of Bluebottle sea drones to signal the same message to the nation's opponents that its jellyfish namesake sends to swimmers: get out of the ocean.
Defence Industry Minister Pat Conroy has announced a $176 million contract with Australian company Ocius Technology to deliver 40 new drones for the navy.
"As when you see at one of our beaches a bluebottle jellyfish, that's a signal to get out of the ocean. I want potential adversaries to realise when they see one of these, it's a signal to get out of our ocean," he told reporters in Canberra on Wednesday.
"That's a really important message about the way we're equipping the Australian Defence Force to help defend Australia and deter."
The boost will bring the number of maritime drones to at least 55, Â giving the nation one of the world's largest uncrewed surface vessels fleets.
The unmanned vessels can stay at sea for lengthy periods, with the longest continuous deployment being more than 180 days.
The Bluebottle drone itself does not require fuel, as it is powered by renewable energy.
Designed to provide persistent intelligence, surveillance and reconnaissance, they will be able to deploy armed aerial drones, and are intended to be used with other capabilities such as submarines.
Bluebottles can be deployed directly from ships and boat ramps to provide flexible options for bases and remote islands.
Mr Conroy said the "formidable asset" was already in use in northwest Australia as part of Operation Resolute, which protects the nation's borders.
"With this world-leading technology, we are able to increase surveillance of Australia's northern approaches and respond to increasing maritime threats," he said.
The fleet can function as a network for underwater defence assets and help provide a communications gateway for submarines.