Papua New Guinea Just Locked Down an Ocean Bigger Than the UK

When Papua New Guinea drew a line around 200,000 square kilometers of tropical sea in May, it wasn’t just protecting a chunk of ocean—it was safeguarding one of the planet’s most remarkable underwater highways.

The newly established Western Manus Marine Protected Area, revealed at the inaugural Melanesian Ocean Summit in Port Moresby in mid-May, sits in the legendary Coral Triangle where the Pacific and Indian Oceans meet. But what makes this 77,000 square-mile reserve special isn’t just its size. The Western Manus region is a biological crossroads: undersea mountains, volcanoes, ridgelines, and canyons that funnel life between shallow coral ecosystems and the deep. Grey reef sharks move through it. Seabirds capable of foraging 200 miles a day hunt its waters. Orcas migrate there seasonally, joining giant deep-sea fish like the yokozuna slickhead, Cuvier’s beaked whale, and over a hundred species of coral in what scientists have called a marine highway connecting two worlds.

The catch? This reserve covers seas that account for about 10% of Papua New Guinea’s tuna fisheries and 6.7% of all fishing output. On paper, that’s a meaningful economic trade-off. But there’s a silver lining backed by research: marine protected areas tend to create a spillover effect. Once fish populations rebuild in protected zones, catch rates actually increase in the boundary areas surrounding the reserve. It’s not a loss—it’s a long-term investment.

The decision came after a two-year National Geographic Pristine Sea expedition documented the Coral Triangle’s biodiversity. What researchers found was sobering: one of the world’s healthiest coral ecosystems, but with clear warning signs. Shark populations were low—a telltale sign of overfishing pressure on apex predators and their prey. Rather than ignore the damage, Papua New Guinea moved to prevent further decline.

Jelta Wong, minister of the country’s National Fisheries Authority, framed the reserve as part of a larger vision: Papua New Guinea is one of the most biodiverse places on the planet, and protecting it ensures the ocean continues to provide food and income. Powes Parkop, governor of the National Capital District and a Manus Province native, put it more personally: Our ancestors have always lived in harmony with the sea, but today, we are writing a new chapter for our children. We aren’t just protecting fish or coral; we are safeguarding our identity.

The Western Manus MPA is part of something bigger still—the Melanesian Ocean Corridor of Reserves, a network spanning Fiji, Vanuatu, and Papua New Guinea that represents a regional commitment to ocean conservation. And it ties to Papua New Guinea’s broader pledge to conserve 30% of its territorial waters. In a world where ocean ecosystems are under unprecedented pressure, that’s not just policy. It’s a statement.