As night fell, the couple followed what countless generations before them had done in dangerous times: They fled into the swampy expanse of the Sudd, where the Nile River’s tributaries bleed into a vast wetland that holds one of the richest collections of wildlife and biodiversity in the world. Behind them, Leer burned.

In Arabic, Sudd means “barrier,” and for centuries the near-mythical wilderness-filled with elephants, giraffes, and eagles-stopped Nile explorers, slave traders, and invading armies at its edge. Now it was providing William and Margaret with sanctuary from soldiers of their own nationality. Two years later, untold thousands remain hidden on its islands, too afraid to return home. Yet this June, South Sudan plans to officially nominate the Sudd as a UNESCO World Heritage site.

In 2011, South Sudan declared its independence from Sudan and became the world’s newest country. Celebrations were short-lived: In 2013, a power struggle between the president, Salva Kiir, and the vice president, Riek Machar, exploded into civil war. The violence engulfed the capital of Juba and traveled 400 miles north to Leer. Expecting it would reach them, William and Margaret hurried to get married. “It’s better to have a wife so you can run together,” reasoned William.

After the massacre, William and Margaret walked all night through waist-high water alongside thousands of other survivors. During the day they hid, subsisting on tree leaves and the black bulbs of water lilies. Margaret feared that snakes and crocodiles lurked under the murky surface, so William attached two branches to a plastic tarp and pulled her in the makeshift canoe. After two weeks they made it to his sister’s home on a small island, where they learned that 600 people had died along the way.

The United Nations estimates that between 65,000 and 100,000 people escaped into the Sudd’s swamps at the peak of fighting. Since then, the situation has deteriorated: cholera hit the islands, a famine was declared-one that experts say is entirely man-made-and the UN warned a genocide may be underway.

In 2016, one year after the attack on Leer, a Kenyan archaeologist named George Abungu addressed a room of South Sudanese government, academic, and military leaders at the UNESCO compound in Juba. The Ministry of Culture had begun to identify potential World Heritage sites shortly after independence and ratified three UNESCO conventions during a break in the current fighting.

Abungu, who has been working on classifying heritage sites in Africa for over a decade, was training the officials to nominate sites for a designation given to Earth’s most important places. From a list of two dozen contenders, a place Abungu had long wanted to visit rose to the top: the Sudd. “It’s basically a natural phenomenon,” he says.

A colonial British governor in the early 1900s compared the Sudd’s expanse to the Sahara Desert. But life thrives in the enormous wetland. More than 400 bird and 100 mammal species call it home, including an annual migration of 1.2 million gazelle and antelope that rivals the running wildebeest of the Serengeti. The Sudd basin spans nearly 14 million acres across the length of South Sudan, and its rains and floods have acted as a climate regulator for millennia.

For the better part of a century, scientists eager to study this vast unknown have been deterred by war. Abungu and the other visiting experts managed to fly over herds of wild elephants crossing South Sudan’s savannas and to drive across stretches of uninhabited wetland in other parts of the country. But the UNESCO team could not get to the Sudd: It was too impenetrable and the conflict too unpredictable.

“Some of the last great wilderness is in South Sudan,” says Paul Elkan, who runs the Wildlife Conservation Society (WCS), the only active conservation NGO doing scientific research in South Sudan. Until recently, the presence of large-scale wildlife in the Sudd was so anecdotal, it was thought to be a rumor. After independence Elkan prepared an aerial survey, lobbied for new environmental protection laws, and drummed up interest from tourism companies. Fighting in 2013 derailed all these plans.

Now, Elkan sees a second chance. “This is the greatest single opportunity to integrate conservation in the foundation building of a country in the history of the world,” he says. After 30 years of working in African conservation, Elkan says he’s never before seen a government as motivated as South Sudan’s, which has a new sense of ownership over resources that have been controlled by outsiders for more than a century.

The French company Total and a joint Chinese-Malaysian extraction project already own oil concessions deep within the Sudd. Surveys by the Nile Institute of Environmental Health, South Sudan’s first environmental think tank, show that water used by local communities is tainted by chemical spills from oil exploration projects. An international NGO recently found that lead exposure in populations living nearby is four times higher than average.

Without a UNESCO designation and the resulting international pressure, Bior Kwer Bior, the Nile Institute’s founder, believes the Sudd will be destroyed. “Our government is too weak to enforce the law it has,” he says. “No oil company is so humanitarian they would do the right thing unless someone is telling them to.” Recently, the government’s oil minister told companies to begin drilling or their contracts would be canceled.

“They think the issues of environment are a luxury,” Bior says of the government. “Environment is not a luxury. If nothing is done to control what’s happening in the oil areas, they’re going to have another war on their hands.”

A food relief helicopter kicks up dust taking off near Kok Island, which hosts thousands of displaced people in the Sudd.

PHOTOGRAPH BY DOMINIC NAHR

But with the threat of oil exploration, it could be placed on a sublist: the World Heritage in Danger list consists of 48 threatened sites that receive special funding and attention. When the Taliban blew up the enormous Buddhas carved into the mountainside of Afghanistan in 2001, the Bamiyan Valley area was ushered onto the list. In 2015, sites in Iraq and Yemen were added. South Sudan’s neighbor, the Democratic Republic of the Congo, has listed four of its seven national parks.

“When it becomes a World Heritage site it becomes the responsibility of the whole world,” says Abungu, who helped Kenya classify some of its six UNESCO sites. He “has no doubt” the Sudd could qualify for immediate placement even before its full size and contents have been measured and its stability assured. He hopes to see it designated within three years.

Not all believe it’s the right move or even necessary. Elkan, who is based in South Sudan, is working to integrate conservation into the country’s laws, and views the World Heritage designation as little more than an honorary title. “UNESCO is bringing people to workshops and saying we want to nominate convention sites-it’s the middle of a war,” he says. “We want to secure the country first.”

In northern South Sudan, the Sudd’s marshes seep into the rebel-controlled town of Nyal. Coconut trees line the red-dirt main road, which hosts an endless game of soccer. There’s never been cell phone reception here or cars, apart from a few humanitarian trucks, and the only way in or out is by canoe or helicopter. Young rebel soldiers in frayed T-shirts with AK-47s slung over their shoulders stroll through threadbare market stalls. Dime bags of salt and tobacco hang from wooden beams; the small chunks of soap are a recent addition.

The shriek of low-flying UN World Food Programme planes raining sacks of sorghum and bottles of gasoline is a welcome noise in Nyal. The town’s population nearly doubled in 2015 when 53,000 displaced people, many from Leer, sought safety during the fighting. Thousands more live in the surrounding islands. When enough food is dropped, two dozen canoe operators hired by Oxfam shuttle people from the islands to the mainland for aid distributions. The closest island is two hours away.

On a drizzly day last May, a fisherman named Ezikiel Wicgoal steered his canoe through a snaking trail of brown water, past banana trees and grazing cattle toward the island where William and Margaret now live. Young boys with spears carried the day’s catch on strings, and men waded knee-deep through the swamp making the long journey to Nyal on the mainland. Fish eagles, South Sudan’s national bird, perched on trees overlooking egrets and storks in the tall grass.

“People were selling their possessions to pay canoe operators, often by going back to their villages late at night and putting themselves in danger,” says Noga Malkin, the former Oxfam coordinator in Nyal. “If there’s a food distribution, people will walk for 10 hours to get to it.”

When Bior Kwer Bior was growing up in a town near the Sudd, his parents told stories passed down through generations about how the untamed wetland had protected its residents. To those who didn’t know their way around, it was considered an impenetrable barrier. To those who did, a hiding spot. “In a sense,” Bior says, “the Sudd wetland serves as a natural refugee camp for people who aren’t able to access international borders.”

This potential World Heritage site is currently filled with thousands of displaced people unwilling to return home without an assurance of peace. Last July, on the eve of the country’s fifth birthday, fresh fighting broke out, forcing UNESCO to cancel its second workshop. But efforts were not abandoned. In June, the government plans to submit a tentative list of sites to UNESCO for international consideration. Someday, the Sudd’s untamed wilderness could redefine the country.

“For now when you talk about South Sudan it’s all about refugees, it’s all about hunger,” says Abungu, the UNESCO consultant. “The question we’re asking in Africa is, how do we use our heritage to silence the guns?”