An iwi leading the fight against a bid to take millions of tonnes of iron sand from the seabed off South Taranaki says there are too many unknown risks.
Ngāti Ruanui is among several groups filing appeals today against the Environmental Protection Authority's decision earlier this month to gave Trans-Tasman Resources' application the go-ahead.
The authority's decision was split, with two votes each way, until the chair cast a second vote, deciding the outcome.
Ngāti Ruanui chief executive Debbie Ngarewa-Packer said the iwi's appeal echoed arguments expressed by the two authority members who voted against the application.
"If you can't be sure of the damage and the data you are providing isn't conclusive, then you can't provide certainty of the conditions because the basis of the argument is flawed from the start."
Forest and Bird and Kiwis Against Seabed Mining confirmed they were also filing appeals today.
Environmentalists fear the seabed mining would threaten blue whales and the extremely rare Māui's dolphin population.
Commercial fishing groups, including the New Zealand Federation of Commercial Fishermen and Te Ohu Kaimoana - which safe-guards Māori commercial fishing interests - have also opposed the application.
Trans-Tasman Resources, which had a previous proposal knocked back by the EPA in 2014, said the project would create about 300 jobs directly and boost export earnings by about $400 million.
Its executive chairman, Alan Eggers, acknowledged the seabed would be damaged, but stressed that it would be restored quickly.