The Green Party says it will set a legally binding target to protect 30 percent of the ocean by 2030 - and lobby to get the Oceans and Fisheries ministerial role to make it happen.
If part of the next government, the Greens would introduce legislation to create an Ocean Commission in the first 100 days, and pass a Healthy Ocean Act in the next three years.
"Without a healthy ocean, we cannot have a healthy planet. It is as simple as that. We cannot have healthy communities, with food to eat, and clean air to breathe, and we cannot tackle climate change," co-leader James Shaw said.
The policy was the final big-ticket announcement from Shaw and co-leader Marama Davidson before the election.
Davidson said the two main political parties have been bickering over inconsequential issues and tinkering, while overfishing, pollution, and climate changed pushed the ocean to the brink.
"Instead of allowing large parts of the ocean to be torn apart for profit, as successive governments have done, the Green Party has a bold, achievable, and brilliantly simple plan: cover large parts of Aotearoa's ocean in protected areas, putting a third of the ocean off-limits to fishing, mining and other destructive industries."
The independent Ocean Commission would work with iwi, hapū, councils, communities, and the public to advise the government, similar to how the Climate Change Commission advises on climate matters.
The advice would feed into the Health Ocean Act, to create a network of marine protected areas covering at least 30 percent of the ocean, and uphold te Tiriti o Waitangi.
A $100 million Moana Fund would support iwi and hapū to deliver on marine conservation priorities most significant to their exercise of kaitiakitanga.
To ensure the policies happen, the Greens say they will lobby in coalition talks to get one of their own MPs the Oceans and Fisheries ministerial portfolio, and get the role into Cabinet.
The portfolio was currently held by Labour's Rachel Brooking, who sits outside Cabinet.
Shaw said while more action had been taken on conservation, waste, and climate change due to the work of Green Party ministers, progress in oceans and fisheries had been too slow.
"Only a Green minister for Oceans and Fisheries will transform how we treat the ocean and help fight climate change, protect the marine life we all rely on, and allow our oceans to thrive," he said.
Brooking, along with Conservation Minister Willow-Jean Prime, recently proposed a ban on bottom trawling in most of the Hauraki Gulf.
The Greens say they would ban it entirely on seamounts and other vulnerable marine ecosystems, along with a ban on recreational set-netting and dredging by 2026, and phasing out commercial set-netting and dredging by 2028.
The policy, which also includes marine research, a marine biosecurity fund, and shellfish bed restoration in the Hauraki Gulf, has been costed at $265.7 million over three years.