Police believe the boat belonging to two missing fishermen has sunk off Cape Jervis, south of Adelaide.
The two brothers-in-law, aged 48 and 44, went fishing in a 4.6-metre half-cabin boat on Sunday morning, and were reported overdue that night.
A life jacket, torch, bucket and foam were found on Tuesday, while an esky and fuel tank were found on Monday about 6.5 nautical miles northwest of Cape Jervis.
The men's families have told police the items were consistent with what was in the vessel.
A large area has been searched by helicopter, fixed-wing aircraft and boats.
Superintendent Les Buckley said the discovery of the items was consistent with the boat having sunk.