A claim for customary rights over all New Zealand's foreshore and seabed has been lodged in the High Court.
However, the Prime Minister said only a handful of the 150 iwi claims to New Zealand coastlines would be successful, and others should not be taken seriously.
Iwi had until 3 April to file claims under the Marine and Coastal Area Act.
The 2011 act allows whānau, hapū and iwi to seek recognition and protection of beaches and waterlines in their rohe. It replaced the highly controversial 2004 Foreshore and Seabed Act.
More than 150 claims for customary rights have been lodged by individuals, whānau, hapū and iwi, including one that covered all New Zealand's foreshore and seabed.
Iwi leader Maanu Paul said he made the application on behalf of all Māori because the Crown had failed in its responsibility to protect the environment and it was time Māori were given back their rights.
"We need an environmentally friendly, sustainable foreshore and seabed.
"You try to fish for eels in our rivers now and there are signs up that say it's polluted, you can't fish for them. We don't want that to happen for our foreshore and seabed."
He said Māori should have control over the taking of fish, council emergency overflows onto the foreshore and oil fracking.
"This government and previous governments have failed in their responsibilities to protect the customary rights of Māori.
"And Māori are saying 'move over, we will take control of this'."
Nothing would change for the average citizen, he said.
Mr Paul said there would be negotiations with the government and the High Court over how customary rights were registered.
The hapū of Motiti Island in Bay of Plenty, meanwhile, said the Crown has failed to protect the ocean and Māori wanted recognition of their taonga.
Prime Minister Bill English said most of the claims would not meet the standard being considered.
"The legislation that's in place makes it quite difficult for those claims to be turned into reality," he said.
"These claims I think are designed to attract attention but I don't think they should be taken seriously.
Mr English said perhaps only a handful of claims would meet the criteria.
"It looks like a bit of a stunt to me. There's been a deadline and a whole lot of claims published - but the legal hurdles for that are very high.
He said however that even if it was a stunt, there was a legal process to be gone through.