It's believed all the containers lost overboard from the grounded ship Rena have now sunk or have washed ashore.
A total of 88 containers fell into the sea, posing a hazard in the shipping lanes.
A flyover didn't locate any more floating containers in the water on Saturday, and no more are known to have toppled overboard.
Port of Tauranga chief executive Mark Cairns, says underwater sonar surveys have been very successful in pinpointing where the containers lie on the seabed. He says the general view is that all the containers have now sunk or washed up on Motiti Island or the beaches on the mainlaind.
Another sonar study will begin at 4am on Sunday to again ensure containers haven't drifted into shipping channels.
The ship ran aground on Astrolabe Reef on 5 October and has spilled up to 350 tonnes of heavy oil, polluting the ocean and washing up on Bay of Plenty beaches and a nearby island.[image:3363:full]
Maritime New Zealand has carried out a preliminary assessment of beaches from Opotiki to East Cape and says there are no reports of oil there at the moment.
Bay of Plenty Beaches closed by the slick will remain off limits until at least Monday.
Only authorised clean up volunteers are allowed on the stretch of coastline between Maketu and Mt Maunganui.
Maritime New Zealand says, on Saturday, there was much less oil on the region's beaches.
But its National On Scene Commander, Nick Quinn, says it's still too early to lift closures. He says the bulk of the oil is still expected to come ashore in areas where it has washed up already, such at Papamoa.
More than 4200 people have so far volunteered to help clean up the coastline.
Health officials say while some volunteers have reported sore throats and dizziness while working on the beaches, no one has been hospitalised with oil-related illness symptoms.
He says people are still advised to stay away from affected areas and avoid the oil.
Beach access will remain closed at least until Monday from Mt Maunganui to Maketu, including Maketu Estuary.
Whakatane District Council said that, on current wind patterns, it expected that oil would be pushed onto eastern Bay of Plenty beaches.
Waste piling up
Several tonnes of bagged waste is awaiting collection from the clean up effort at Newdicks Beach, Maketu Beach and the local estuary over the past three days.
The Newdicks Beach clean-up team leader, Barry Watkins, says it's frustrating none has been taken away despite repeated calls to authorities.
He says it need to be collected before any oil leaches into the ground, and adds that rats have already been attracted to the waste because of the dead birds inside.
Rare species among birds killed
More than 1100 dead birds, including rare species, have washed up on the Bay of Plenty coastline since the Rena began leaking oil last week.
Forest and Bird says the most common dead birds include the diving petrel, fluttering shearwaters and Buller's shearwaters.
However rare species - such as mottled petrels, blue petrels and Antarctic prions - are also among the dead.
Karen Baird of Forest and Bird says most oiled birds are now sinking to the ocean floor.[image:3362:third:right]
Boat ramps off limits
The remainder of Tauranga's recreational boat ramps are being closed indefinitely.
Maritime New Zealand says it has asked the city council to shut down the seven ramps used by boaties on the city's beaches until further notice.
Four of the ramps had earlier been closed as part of efforts to keep oil from spreading on the beaches and to enforce a large exclusion zone around the stricken vessel.