Australia says a current mission along the coast of Bougainville island is a preliminary step towards ensuring safer waters in the region.
The Australian ships HMAS Shepparton and HMAS Benalla are surveying the sea waters along the west coast of the island, from Torakina to Buka, in preparation for another chapter of Operation Render Safe.
Australia's hydrographer Commodore Brett Brace says the aim is to remove all the Second World War unexploded ordnance from the Pacific, and the operation carried out extensive work in the Solomon Islands last year.
He says the ships are detecting items on the sea floor so other ships can safely remove bombs and other military debris later in the year.
"They're fitted with the latest multi-beam sonars and positioning technology, to enable them to effectively sweep the sea bed using sound, so sonar, to look for navigation hazards such as coral reefs, bombies, wrecks, to make sure that they can declare an area safe for shipping."
Commodore Brett Brace says he will turn the information into updated navigational charts.