Bogda Mountains - The Turpan Depression, nestled at the foot of China's Bogda Mountains, is a strange mix of salt lakes and sand dunes, and is one of the few places in the world that lies below sea level. Delta Region, Netherlands - Along the southern coast of the Netherlands, sediment-laden rivers have created a massive delta of islands and waterways in the gaps between coastal dunes. Brandberg Massif - Rising unexpectedly from the heart of the Namib Desert in northern Namibia, the Brandberg Massif is an exhumed granite intrusion. Desolation Canyon - Utah's Green River flows south across the Tavaputs Plateau (top) before entering Desolation Canyon (center). Ganges River Delta - The Ganges River forms an extensive delta where it empties into the Bay of Bengal. Great Salt Desert - Like swirls of paint on an enormous canvas, shallow lakes, mudflats, and salt marshes share the sinuous valleys on Iran's largely uninhabited Dasht-e Kavir, or Great Salt Desert. Great Sandy Desert - The western region of Australia's Great Sandy Desert is in an area almost devoid of sand, but characterized by complex geology. Great Sandy Scars - In a small corner of the vast Great Sandy Desert in Western Australia, large sand dunes --the only sand in this desert of scrub and rock -- appear as lines stretching from left to right. Konari, Iran - The Mand River and the small town of Konari nestle in the Zagros Mountains in western Iran. Lake Disappointment - Surrounded by sand dunes, Lake Disappointment is an ephemeral salt lake in one of the most remote areas of Western Australia. Lena Delta - The Lena River, some 2,800 miles (4,400 km) long, is one of the largest rivers in the world. The Lena Delta Reserve is the most extensive protected wilderness area in Russia. Mississippi River Delta - Turbid waters spill out into the Gulf of Mexico where their suspended sediment is deposited to form the Mississippi River Delta. Namib Desert, Namibia - Namib-Naukluft National Park is an ecological preserve in Namibia's vast Namib Desert. Coastal winds create the tallest sand dunes in the world here, with some dunes reaching 980 feet (300 meters) in height. Niger River, Massina Mali - Coursing through parched, landlocked Mali in Western Africa, the Niger River skirts the edge of the dune-striped Sahara before turning sharply south to join the Bani River. Tides and ocean currents in the Bahamas sculpted the sand and seaweed beds into these multicolored, fluted patterns in much the same way that winds sculpted the vast sand dunes in the Sahara Desert. The Optimist, Kalahari Desert, Namibia - On the edge of the Kalahari Desert in Namibia, sand dunes are encroaching onto once-fertile lands in the north. Parana River Delta - The Parana River delta is a huge forested marshland about 20 miles northeast of Buenos Aires, Argentina. The Parana River delta is one of the world's greatest bird-watching destinations. This image highlights the striking contrast between dense forest and wetland marshes, and the deep blue ribbon of the Parana River. Syrian Desert - Between the fertile Euphrates River valley and the cultivated lands of the eastern Mediterranean coast, the Syrian Desert covers parts of modern Syria, Jordan, Saudi Arabia, and Iraq. Ugab River - Elusive, but ecologically vital, Namibia's Ugab River only flows above ground for a few days each year. The subterranean waters underlying this ephemeral river, however, are shallow enough in places to fill hollows and sustain a wildlife population that includes the rare desert elephant. Volga River Delta - Where the Volga River flows into the Caspian Sea, it creates an extensive delta. The Volga Delta is comprised of more than 500 channels, and sustains the most productive fishing grounds in Eurasia.