With a guilty plea after the Rena discharged hundreds of tonnes of hazardous material now made, the ship's owner says it's now focusing on what to do with the wreck.

Daina Shipping Company was fined $300,000 in Tauranga District Court on Friday after admitting a Resource Management Act charge for discharging a harmful substance into a coastal marine area.

The charge was laid after the Liberian-flagged container ship spilled 350 tonnes of heavy fuel oil into the ocean after it struck the Astrolabe Reef off Tauranga on October 5 last year.

In deciding on the $300,000 fine, Judge Robert Wolff said the pollution was not deliberate and the Greek company had continued to co-operate with the community and government agencies.

In a deal separate to the court action, Daina Shipping agreed earlier this month to pay $27.6 million for the costs incurred in the clean-up, an amount which could increase to $38m if it's decided to leave part of the wreck in place.

"With input from the local community, we are also moving to determine the most safe, practicable and responsible way to deal with the wreck. Dealing with the wreck should be the final chapter of the Rena accident," company representative Konstantinos Zacharatos said.

Mr Zacharatos apologised again for the incident, saying nobody wanted it to happen, but that the company took had used all its resources available to limit the damage and felt a good job had been done, with the assistance of the Tauranga community.

Lawyer Paul Mabey said Daina Shipping, through its insurers The Swedish Club, has paid $235 million since the grounding and is continuing to pay for salvage.

Maritime New Zealand director Keith Manch welcomed the admission, saying it led to the case being resolved in a timely fashion.

The ship's former master Mauro Balomaga, 44, and navigation officer Leonil Relon, 37, were sentenced to seven months' jail in May on charges relating to the grounding, the pollution and attempting to cover up navigation errors.