Niue is one of the smallest island nations in the world. But its surrounding ocean is as big as Vietnam, home to grey reef sharks and a rare sea snake called the katualiThe highly venomous snake is one of the most potentially dangerous creatures on the planet. It is only found in the island's honeycomb of underwater caves. .

The Polynesian island has unveiled plans to protect 100% of its waters. New rules limit fishing to specific zones. The government will allow traditional canoes and scuba diving in designated areas to support communities and tourism.

"The ocean is everything to us," says the island's premier Dalton Tagelagi. But it is under threat. Global warming is bleaching the coralRising sea temperatures cause coral to expel the algae that give them colour and provide them with nutrients. The coral dies and the reef habitat collapses. as storms batter its reefs. Illegal and commercial fishing have damaged its ecosystems.

The idea of marine protected areasThere are more than 11,000 marine reserves globally, each offering different levels of protection. The largest is Papahanaumokuakea which protects the ocean water around Hawaii.  is not new. But the movement is growing, as conservationists push to protect 30% of our oceans by 2030. Currently, only 2.4% are fully protected. "It is very optimistic to think we'll reach '30 by 30,'" says fisheries scientist Patricia Majluf.

Can marine parks save our seas?

"All they do is cause fishing to go elsewhere," says researcher Ray Hilborn. Three billion people depend on fish as their primary source of protein and critics say "no-take" areas harm communities who rely on the oceans.

But the biggest problem is cost. One study estimates a fifth of all fish is caught illegally. Niue has no navy and counts on its neighbours to police its waters. And poorer countries say they need the income from fishing and cannot afford to leave the ocean alone.

Research suggests small marine parks help revive fish stocks and cut carbon emissionsWhen a gas is let off from something, like a car, it is an emission. Carbon dioxide, or CO2, is a greenhouse gas that contributes to global warming.. Creating safe harbours and protecting spawning groundsIn order to lay their eggs, sealife may travel up to 3,000km to return to where they hatched. Damaging these sites can have a catastrophic effect on population sizes.  could boost the annual global catch by eight million tons.

"The only way to get more food from the ocean is to protect more," says marine ecologist Enric Sala. Researchers in the Gulf of California found the most successful projects worked closely with fishing communities.

The documentary Seaspiracy predicted oceans would be "virtually empty" of fish by 2048 if current trends continue.

The oceans are fundamental to regulating the Earth's climate and the water cycle. "We are doing our part to protect what we can for our future generation," says Premier Tagelagi, "just as our forefathers did for us." The survival of life on Earth depends on protecting its marine ecosystems.

Yes: Nature is resilient. It will bounce back if given space to recover. Scientific research helps target the most vulnerable ecosystems. And new technology like drones can stamp out illegal fishing.

No: These reserves do nothing to stop the amount of plastic and industrial waste dumped in the oceans. Or the rising demand for food and resources. Unfortunately, this is too little, too late.

Or... Maybe. If low-income countries in the Pacific can afford to protect their seas, wealthier nations may follow. But it will involve even more changes to what we put in the ocean and what we take out.