Ironsands Offshore Mining Ltd has been given a five-year permit to explore for seabed minerals across 220sq km off the New Plymouth coastline.
The permit was granted on May 8 by the Ministry of Business, Innovation and Employment's New Zealand Petroleum and Minerals. It lasts five years, and will allow exploratory drilling.
The area overlaps one end of the large West Coast North Island Marine Mammal Sanctuary, which was created in 2008. It was made specifically to protect critically endangered Māui dolphins.
There are 55 to 75 of the dolphins left alive in the wild, Radio New Zealand reported.
Greenpeace and the Ngāti Ruanui iwi are shocked and outraged by the approval.
Ngāti Ruanui chief executive Debbie Ngarewa-Packer said sediment from any mining done there would drift south into the tribe's rohe (area). She is questioning the Green Party's influence on government.
The Green Party has the conservation and associate environment portfolios, and it has a commitment to steering away from fossil-fuelled extractive industry, she said.
But Green Party Conservation Minister Eugenie Sage told Radio New Zealand the permission was out of her hands. It is possible under the rules of Taranaki Regional Council's coastal plan.
She said the Conservation Department would get involved if the company went on to ask for a mining permit. She said she was totally committed to a Taranaki marine mammals sanctuary.
Greenpeace is calling on the Government to reject all attempts to mine the seabed.
Ironsands Offshore Mining Ltd intends to export iron-sand concentrate. It was founded in Auckland in 2008.
The methods it intends to use could be similar to those proposed by Trans-Tasman Resources.
Because the area it has chosen is closer inshore than the area Trans-Tasman Resources proposes to mine near Pātea, it could cause more noticeable damage.
The company comes under the umbrella of CASS Offshore Minerals Ltd, which also umbrellas Pacific Offshore Minerals Ltd.
That company has a permit to look for ilmenite, silver, gold and iron in another large area offshore from Waihi in the Bay of Plenty.