About 1300 tonnes of the Marmite-like gunk was eventually recovered.
Then came the careful plucking of towers of leaning containers from the decks, and getting at those which could be got at below decks. The last few accessible ones had to be yanked from mangled holds.
Now, Resolve Salvage and Fire is set to begin one of the most dangerous phases yet - sending divers underwater in a sweeping sea to hack the bow away to a metre below the tideline.
Up until now, the going has been comparatively simple.
The bow has been on a steep list and rocking amid swells, but at least the salvage team have had something to stand on while carving it up piece by piece before ferrying it back to land by helicopter.
When the number of flights is added up - more than 400 for the individually heli-lifted chunks of steel, plus four in and out each day for the crew for the past 45 days - the business gets particularly expensive.
Recently, just 20 litres of diesel had to be flown out to the site by a helicopter. The kind of fuel it was using costs $100 a litre.
But there have been results: more than 650 tonnes of steel no longer belong to the Rena.
It's all been shipped to a Tauranga scrapyard for recycling, and somewhere among the pile is the piece bearing the ship's cursed name - nobody bothered to keep it for a souvenir.
Across town at the Port of Tauranga, a large dive barge is being assembled for the next stage, which salvage master Frank Leckey said would slacken the pace.
"You get the adrenaline going and you get steel being brought off, but now we're getting to the diving end and it slows down to a quarter of the speed."
He reckoned a break in the weather and the chance to whisk away another 100 tonnes of the Rena would boost morale again.
For the Resolve salvor, the working day begins at 8am and is spent trooping along specially welded steps on the wreck's steep angle, with a brief adjournment for lunch.
"Half [of the salvors] break and have 30 minutes for lunch, then the next half breaks, and they're all back to work - they can't go anywhere because they're all sitting in the same spot."
The unimpeded bluster off the ocean smacks the skin, but the workers don't bother with balaclavas.
The bow's list, now at 35 degrees, poses a much more serious problem - balancing its continually lightening weight against the threat of rolling gets serious consideration.
Divers keep out of the wreck in any swells higher than a metre and those treading the wreck are clad in lifejackets, with life rafts on standby.
"What happens," says Mr Leckey, "is the whole ocean is coming over in a big lump, but as it goes through the wreck it has to come out again - it's like a suction cup and will push the diver in and drag him back out again."
Mr Leckey, who has decades of experience in salvage around the world, put the Rena within the 10 most challenging salvages ever.
"Just the weather conditions on the Rena itself are very harsh - we expected it was going to be bad, but sometimes it's a little bit worse than we thought it was going to be."
If conditions are too rough, the crew stay on shore. "As a matter of fact, we can tell the weather by the surfers - if they're up there in big waves, there's no sense in us going to work because it's really bad out there."
There have been setbacks - some crucial gas-cutting gear falling into the water with a 250-tonne chunk of hull last month - and there are bound to be more.
But Mr Leckey is confident of finishing the job and flying back to Florida by year's end.
"I still have this feeling I'm going to be home for my New Year's party. The way it's going now, even with some delays, I think we're still going to make our mark, or fairly close to it."
Monitoring reveals wildlife recovering well from oil
Many hundreds of birds perished in the Rena's oil - but reports show populations may have bounced back.
Massey University, which helped set up a special wildlife centre during the crisis, has been tracking little blue penguins and endangered dotterel that were rescued and temporarily kept in captivity.
The more than 360 oiled little blue penguins that were cleaned and released back into the wild have begun breeding season and it appears a normal number of nests are occupied.
Six dotterels died after the disaster and to date, 43 of the 56 birds that were caught and released have been seen again. Monitoring over the upcoming breeding season is expected to account for those not seen yet.
The response centre received around 409 birds at the height of the disaster and of the 2410 dead birds collected, 1448 were oiled.
Ecosystem could integrate Rena wreck: salvage leader
The man leading the Rena's salvage believes the ship could mesh into Bay of Plenty's ecology if it is left on Astrolabe Reef.
Leaving part of the Rena in place has been mooted as an option by the Rena's owners, who would pay an extra $10.4 million to the Government if it gained resource consent for the wreck to remain.
Diving groups are pushing for this, saying it has tourist-pulling potential, but the suggestion has stirred debate in the Bay of Plenty.
Many in Tauranga, including local iwi and the hapu of Motiti Island, want the wreck gone. One ecologist describes it as a "floating toxic warehouse".
But Resolve head salvor Frank Leckey said the Rena could one day teem with marine life. Concerns had been raised about anti-fouling paint on the hull, but he doubted this would cause any harm.
"I believe the aft-section will create more fish and there'll be a lot of growth on it," Mr Leckey said.
Firm makes good on $1 million donation promise
The charterer of the Rena has finally confirmed a $1 million donation to the Bay of Plenty community, nearly a year after it was announced.
The Mediterranean Shipping Company (MSC) pledged the money as a voluntary donation just two weeks after the grounding, but had been held up until negotiations between the Government and the Rena's registered owners were settled.
A deal involving $27 million for cargo owners who lost goods was confirmed this week. But Phil Abraham of MSC New Zealand said he expected there would continue to be claims on the cargo.
The donation from MSC, which had no liability over the disaster, would go towards cleaning up the Bay of Plenty waters and coastline to reduce the negative effects of the grounding, including the spilling of oil and debris.
It would also assist local iwi, caring for affected wildlife and local tourism-related businesses which bore losses as a result of the disaster.
