The desert is reclaiming buildings in Kolmanskop, a Namibian ghost town that was once home to a working diamond mine.
Namibia is about the size of Texas and Louisiana combined and home to about 2.1 million people, but vast stretches of its arid landscape are extremely uncrowded.
Cradle Mountain-Lake St. Clair National Park in Tasmania is one of many Australian areas well-protected from human pressures
Australia is almost the size of the U.S.'s lower 48 states, and there's certainly no shortage of people living in the country—almost 22 million to be exact. But most Australians live in the coastal communities that ring a massive and relatively empty interior.
Iceland is home to a relatively homogenous population with few significant recent migrations, the UN's Gerland said. "In recent decades it has also stood out in Europe as one of the places where people live to a very old age"—echoing a global trend toward graying populations, according to the UN.
Population densities here are only about three people per square kilometer, according to UN stats, but the Center for Sustainable Destinations' Tourtellot said the beautiful summer season is a bit busier.
Along a creek in South America's Suriname, otters have stripped the vegetation from this site to mark their territory—and humans are unlikely to trespass.
Giant otters are just part of the wild diversity of plants and animals found in the uninhabited tropical rain forest that covers most of this former Dutch colony, which is about the size of the U.S. state of Georgia and home to fewer than half a million people.
Suriname is trying to leverage its vast natural advantages for a growing rain forest ecotourism sector, Tourtellot said. But those same resources also fuel industries such as logging and mining in the interior.
Camels compete for a meal at a former oasis—now overtaken by desert—in Mauritania. Also eager for water, most of the country's 3.2 million people live in cities or along the Senegal River, though there is a population of traditional desert nomads, said the UN's Gerland.
Mauritania's tourist sites—including enormous sand seas, ancient cities, and empty coastlines—have taken a major hit in recent years due to safety concerns in the wake of terrorist attacks on travelers.
Reference source: nationalgeographic.com