A battered and worn oyster barge has successfully completed the notorious trip across the Tasman, turning up in northern Australia one year after it went missing from New Zealand.

The barge, which was reported missing from Houhora in the Far North region of New Zealand in August last year and suspected stolen, has been found between Cape Bedford and Cape Flattery in far north Queensland.

It was found riddled with cracks and holes in the hull and the finder, Ross Garnsey, says it's amazing it had managed to stay afloat for the entire journey.

Damage to the barge's motor suggests it spent some of the voyage upside down, Mr Garnsey said.

The vessel, called the Facilitator 2, was believed to have been stolen when it went missing last year, with several sightings being reported but not confirmed.

Houhora police Constable Tracee Knowler said it was unknown if the barge had in fact been stolen, or whether it had broken its mooring.

"It may be difficult after all this time to determine how the barge ended up so far from home," she said.