The wreck of the Rena is still grinding its way through the courts, six years after the container ship ran aground on Astrolabe Reef and unleashed New Zealand's worst maritime environmental disaster.

October 5, 2011, is burned into the memories of the thousands of Tauranga people who responded to the black tide of oil leaking from the stricken vessel. They painstakingly cleaned the beaches and saved oil-encrusted wildlife.

But the Environment Court ruling this year to allow the wreck to remain on the reef has struck fresh controversy over the issue of what would happen if big chunks of the Rena's bow broke off in storms.

Lawyers acting for the parties involved in the appeal are waiting to see how Judge Jeff Smith responds to feedback on some of the suggested conditions that underpinned the decision to leave the Rena on Astrolabe.

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The appeal against the Bay of Plenty Regional Council's original decision to leave the remains of the wreck was taken to the Environment Court by Motiti Island's Ngai Te Hapu and Papamoa hapu Nga Potiki.

Tauranga lawyer Paul Cooney, who represented the regional council, said the court had suggested changes to some of the conditions put forward by parties to the appeal, and invited them to respond.

Included was a condition requiring the Rena's owner to remove pieces of the bow weighing up to 20 tonnes that broke off. The remaining bow section of the wreck was lodged on a shallower portion of the reef.

"It is not over yet."

Matthew Casey, QC, the lawyer acting for the owner and insurer, said they had taken expert salvage advice on recovering a piece weighing up to 20 tonnes and found that it was not as straightforward as the court thought it might be.

He said there was no salvage equipment in New Zealand that could handle that sort of job at that location, and it would cost $12 million to bring in kit from Singapore. The insurer had already spent $650 million on the salvage and to settle with the Crown.

The owners were seeking that the weight be reduced to 5 tonnes. Mr Casey said a piece weighing 20 tonnes would need to be cut up before it was lifted using a crane mounted on a barge that had massive anchor systems.

Iwi groups who supported the consent to leave the wreck did not want more salvage work done on the bow because it caused more harm than good to the reef, he said.

Mr Casey said the good news was that the wreck was fairly stable, with no movement recorded during the storm that hit while the Environment Court was hearing the appeal in March-April.

Russ Hawkins, club captain of the Mount Maunganui Underwater Club, said club members diving the wreck had not noticed any changes to its position on the reef.

He said the wreck was becoming a thriving marine habitat. He noted how on three occasions Judge Smith, looking at underwater photos, had asked whether he was looking at the wreck or the reef.

Tom Bennion, the lawyer acting for Ngai Te Hapu, said his client's bottom line was for the whole wreck to be removed. If Ngai Te Hapu had to live with the wreck staying on the reef, it preferred that the maximum was taken away if sections broke off.

He said there was still the potential for someone to appeal the decision to leave the wreck, once the court had ruled on the conditions. It would have to be on a question of law.

"This whole thing was breaking new ground. Potentially, there is a little way to go yet."

Key dates in Rena Disaster
October 5, 2011: Ship hits Astrolabe Reef 2.20am
October 10, 2011: Oil starts washing ashore on Tauranga beaches
January 2012: Rena breaks in half