The owners and insurers of the MV Rena want to leave part of the cargo ship on the Astrolabe Reef - but Tauranga's Mayor would rather have the whole wreck gone.

The cost of dealing with the ship, smashed into pieces on the reef off the Tauranga coast, has now shot past $275 million and is set to become one of the most expensive maritime salvages in history.

Yesterday, the Rena's owners and insurers flagged a proposal to leave part of it on the reef, where it has remained since October 2011.

The proposal involved an application for resource consent to leave part of the wreck in place following work that would secure the site.


This year, the insurers plan to remove contaminants to meet environmental guidelines, take away as much remaining cargo as possible and clear or close any hazards making the wreck unsafe for diving.

Under the proposal, some debris would remain around the site, and a discharge consent would have to be sought to account for slow release from the weathering of wreck steel and paint, residue oils and any lingering cargo contaminants.

The insurers said the site would be monitored regularly, and pollutants would have a "minimal and temporary" effect. However, they said some contaminants from remaining cargo, hull paints or oils could affect the sea floor, potentially "restricting some ecological regeneration".

If the company gained consent it would establish a "restoration package" to fund a range of research scholarships and grants for projects in the Bay of Plenty.

Removing the entire wreck would mean extending the period the exclusion zone would need to remain in place, involve greater disturbance to and destruction of the reef environment and "major operational challenges" including risks to workers, the ship's owner and insurers said. A previous assessment estimated that option could take up to five years.

The New Zealand Underwater Association has pushed for the wreck to become a dive site, but Tauranga Mayor Stuart Crosby said his first preference was to have the ship completely removed. If that was not possible, he could accept the site being made safe with strict consent conditions and "a strong and robust" monitoring programme.

Motiti Islander Aubrey Hoete was comfortable with the proposal, but most iwi on the island wanted it gone, he said.

The insurers acknowledged the cultural and spiritual bond the island's Te Patuwai hapu had with the reef, Otaiti, and were "committed" to working with them and other iwi groups to address concerns.