Three salvage crew members will remain on board Rena overnight to continue pumping oil off the wrecked ship.

The 47,000-tonne cargo ship ploughed into the Astrolabe Reef off the coast of Tauranga on October 5, spilling more than 350 tonnes of oil and dozens of containers into the sea.

Salvage crews have pumped about 70 tonnes of oil off since the container ship became grounded, but bad weather could jeopardise the operation overnight, Maritime New Zealand says.

Close to 1300 tonnes of oil remains on board.

Svitzer Salvage team leader Captain Drew Shannon said the main priority was the difficult task of removing oil from the wrecked ship.

“We are also working feverishly in the background with planning and logistics on the removal of containers."

A booster pump is likely to be operating by this evening, while a steam unit is already making it easier to remove the oil, he said.

Shannon did not want to speculate on the effect tonight's predicted bad weather may have on the Rena.

National On Scene Commander Nick Quinn said the swell was expected to reach up to 2.5 metres with the 30 knot winds hitting tonight.

Meanwhile, "patties" of oil from Rena have been found as far away as White Island today.

“There's been a light amount of oiling, although because it's weathered, emulsified oil in the form of palm sized patties, they’re relatively easy to collect and remove,” Quinn said.

Oil was expected to wash up along the coastline towards East Cape in the coming days.

Workers were helping to clean up White Island, Quinn said.

OIL POSSIBLE AT OPOTIKI AND EAST CAPE - NIWA

The National Institute of Water and Atmospheric research today said oil could wash ashore at Opotiki and East Cape beaches later this week, as strong wind currents continue to push it in an easterly direction.

NIWA released a video showing where oil leaked from the grounded cargo ship Rena is expected to end up.

It shows the leaked oil engulfed Motiti Island's coastline, was pushed ashore on to Tauranga beaches and then started moving in a south-east direction late last week, giving the beaches some much-needed respite.

Forecasted wind currents were expected to drive the oil towards the coast overnight, and then continue moving it eastward, NIWA principal scientist Mike Revell said.

The northerly forecast could push the oil as far as Opotiki and the East Cape.

"It will drift towards the shore but not for too long - only 12 hours - and then it will continue in an easterly direction," Revell said.

It was expected to be pushed towards the shore from 7pm today.

The video shows little red dots, representing oil, being released into the ocean from the ship's location and then tracked, according to wind currents.

'HAIRY' SITUATION ABOARD RENA

MNZ salvage head Bruce Anderson said crews would work as fast as they could to get oil out of Rena, but it was not an easy job.

"At the moment they are pumping Marmite through a three inch (7.6cm) hose over 160 metres," Anderson said.

"The salvors are boosting and tweaking their system. They will keep transferring oil for as long as they possibly can."

Three salvors had stayed on the vessel through the night, after providing an evacuation plan, and nine were on board today.

"It was hairy. This thing is creaking, groaning, it's a vessel dying."

The ship had broken up and was sitting on the reef in two parts, he said. However, this afternoon MNZ said that was not the case. "Salvage experts advise that while the Rena is cracked port and starboard, it remains together in one piece and is in the same position as it has been for the past week."

Anderson stressed the situation was still precarious, and a swell had been been putting pressure on the hose between the Rena and the ship Awanuia.

"We are going to have quite choppy seas overnight and I wouldn't be surprised if we lose more containers overnight," he said.

"The main thing about the weather is being able to keep the Awanuia stable [beside the Rena]," Anderson said.

"We are anticipating there will be problems with the transfer later on"

If the salvors had to evacuate the ship, the would seal the fuel tanks, he said.

"The last thing they want is to cause a spill"

The windy conditions could also push more oil onto the coast overnight and push containers further out to sea.

There have been containers spotted as far east as White Island and they were currently being corralled in two spots, one near Mt Maunganui and the other off Motiti Island

Officials said earlier that more oil will leak from the ship.

The warning came as forecasts predicted winds of 25 to 35 knots later today.

"Night-time operations have given us additional lead time, particularly given the expected change in weather conditions forecast for later today," Anderson said.

"The team has encountered a number of technical difficulties, but the calm conditions and the forecast for the next 24 hours give them a good opportunity to get this work under way."

"This is a hugely challenging and risky operation even in full daylight – these are incredibly brave and dedicated people working very hard to protect the beaches and coastline of the Bay of Plenty and the communities who use them."

However, Anderson warned people to expect more oil to spew from the Rena. "How much oil we don't know yet, when, we don't know yet."

The Rena was precariously placed, with around 60m of the vessel hanging off the reef into deep water. "The only thing holding that vessel ... is the buoyancy of all the air in the engine room. There is every chance the vessel could slip off the reef."

BEACH REOPENS

Yesterday, some locals rejoiced after officials reopened a section of beach previously closed due to the oil spill. But many beaches still remain closed and there is a ban on swimming.

The small area of beach between Mt Maunganui along to Moturiki Island was opened after assessments of the beach and water quality were deemed clear.

Hamilton man Greg Gerrand and his son Rhys, 6, were pleased to finally get to the beach.

"We were quite gutted because the kids love playing on that beach.

"You can see the ship on the horizon and you can see the oil on the sand."

Transport Minister Steven Joyce, who spent yesterday in Tauranga, was meeting Kevin Clarke, the Australasian managing director of Mediterranean Shipping Company, which leased the Rena, in Wellington this morning.

"I'm just hoping to get a much clearer view as to how they view their involvement. I think it's important to have a reasonably frank discussion with them as to how they see their role in this."

About $4 million had been spent on oil clean up operations, but that did not include the cost of salvage.

Fisheries Minister Phil Heatley spent yesterday meeting commercial fishing operators who worked in the exclusion zone around the Rena.

He said his team was working very closely with the chamber of commerce to get a good picture of the affects of the disaster.

He would receive a report this week on the impact of the commercial fishing industry.

Fish caught in an oil exclusion zone - between Mt Maunganui and Maketu - cannot be sold for safety reasons and the Government was considering offering support to the commercial fishing sector.

- Fairfax NZ