A huge clean-up is underway on the mid-north coast after piles of debris washed up from shipping containers that fell off a cargo ship off the New South Wales coast during rough seas.

Nappies, sanitary products and surgical masks were among the flotsam that washed up after 83 containers fell overboard from the YM Efficiency on Thursday, about 30 kilometres off the coast of Port Stephens.

Sorry, this video has expired Over 80 containers fall from a cargo ship off Port Stephens

Volunteers have been clearing carloads of debris from Jimmys and Bennetts beach at Hawks Nest since Sunday morning.

Late Saturday afternoon, marine rescue authorities spotted four containers about one kilometre offshore of Hawks Nest on the mid-North Coast, Roads and Maritime executive director Angus Mitchell said.

Debris was also found inside Port Stephens at Rocky Point near Anna Bay and at Fingal Head, while a section of shipping container was also located at Yacaaba Headland.

Mr Mitchell said there had been no reports of any further containers lost by the ship.

Rolls of paper from the cargo vessel YM Efficiency washed up at Yacaaba Headland. ( Supplied: Roads and Maritime Services )

Ute-loads of rubbish collected

Hawks Nest resident Julie Sims said dozens of locals and holidaymakers have collected items including containers of emu oil, toilet-paper packaging, thousands of red foil lolly wrappers and clocks still in their packaging.

Debris was washing up from Fingal Bay to Jimmy's Beach as well as Nelson Bay inside Port Stephens.

Toilet paper packaging, clocks and lolly wrappers were among the debris. ( Supplied: Brooke Feltis )

"It's everywhere, we only did a 200-metre stretch today before the tide came in, but as the tide was coming in more plastic was washing in with it," she said on Sunday, adding that several utes had been filled with the debris.

"It's the tip of the iceberg, this was literally the first wave of rubbish … it's going to take weeks or months before this is finished."

"Standing on the beach it's just horrendous. It's heartbreaking to see in this pristine location."

Ms Sims said a lot of the plastic was becoming caught in the seaweed and needed to be pulled out by hand.

Mr Mitchell warned anyone looking to scavenge the debris that they had no right to do so.

"Members of the public are reminded items recovered from containers remain the property of the consignor and can't be salvaged," he said.

Boaters are being warned via marine radio to look out for the 12-metre containers.

Cargo ship waiting for berth

Managing director of Yang Ming Marine Transport Corp, Steven Ka, said the YM Efficiency was currently off Sydney, waiting for the port to open.

He said the company was doing everything it could to secure a berth as soon as possible.

Mr Ka said there had been no dangerous cargo or hazardous material within the containers.

Along with the 83 containers lost, 30 had collapsed and remained on deck, Mr Ka said.

He said the vessel itself had not been damaged, although deck fittings would need to be repaired.