Opponents of a proposal to mine millions of tonnes of iron sands from the Taranaki seabed have resumed their attacks in the final day of hearings on the project.
Trans-Tasman Resources wants to dig five million tonnes of iron ore from the seabed every year for the next 35 years.
Two lobby groups, Greenpeace and Kiwis Against Seabed Mining (KASM), want the scheme blocked by the Environmental Protection Agency.
KASM representative Ruby Haazen told the EPA hearing this morning a plume of mined sediment would harm the sea and sea life.
"Marine mammals is the most egregious example but the most fundamental example is the plume," she said.
"The applicant knew how central it was, yet this hearing was delayed and thrown out of kilter by the need to re-run a worst case scenario, which for reasons we have canvassed was not worst case."
Ms Haazen said the worst case did not stack up economically either.
The company will make its final statement this afternoon.