A four wheel drive vehicle crosses the sand dunes in the late afternoon sun near Egypt's western desert oasis of Siwa on February 3, 2002. (Reuters)

Members of a group of Maltese mountaineers, training for a charity climb up Tanzania's Mount Kilimanjaro, reach the summit of Sicily's Mount Etna, the largest and most active volcano in Europe, as toxic sulphur fumes spew all around them October 16, 2005. (Reuters)

Tourists rest above a hill in Valle de la Luna (Moon Valley) located inside the nature reserve of Los Flamencos in the Atacama Desert, near San Pedro de Atacama in northern Chile, April 27, 2005. (Reuters)

A youngster walks along the banks of the Merced River, in view of El Capitan (L), and Bridalveil Fall (R) in Yosemite National Park, California May 17, 2009. (Reuters)

A boat sails at sunset through an area on the Yangzte River in the Hubei Province near the town of Badong in central China November 5, 2007. (Reuters)

Tourists ride camels in front of Giza pyramids on April 23, 2006. (Reuters)

Sunlight reflects on the rails of the 5 California Zephyr Amtrak train in Nevada June 14, 2008. (Reuters)

A flooded road is seen near the Nueva Imperial town in southern Chile September 3, 2008. (Reuters)

The downtown core of Vancouver and the Lions Gate Bridge rise above a morning fog in this view from Cypress Mountain in West Vancouver, British Columbia November 17, 2008. (Reuters)

Skaters play one of Canada's oldest winter pastimes, pond hockey, on the frozen surface of Lake Louise just outside the small village of Lake Louise, Alberta November 27, 2007. (Reuters)

A lone fisherman stands atop a rock outcrop below Sydney's North head at dawn February 6, 2007. (Reuters)

People swim in the Celeste river waterfall at Tenorio Volcano National Park in Upala March 18, 2008. (Reuters)

A Zambian man somersaults into a pool at the edge of the 110 metre high main falls of the Victoria Falls on the Zambezi River which forms the border between Zambia and Zimbabwe October 10, 2004. (Reuters)

A view of sulphur and mineral salt formations created by the upwelling springs of Dallol volcano in this picture taken November 29, 2004. (Reuters)

The wind blows desert sand with Dubai's iconic landmark and world's tallest hotel, the Burj Al Arab, in the background February 8, 2007. The Burj Al Arab sits on its own man-made island, stands 321 meters (1053 feet) high, and resembles a billowing sail. (Reuters)

The world's largest salt flat, the Salar de Uyuni, is seen from Incahuasi island in the south of Bolivia at 3676 meters above mean sea level, August 21, 2008. (Reuters)

Tucked in the valleys and forests of Swaziland's remote Lebombo mountains are hundreds of hidden marijuana plantations, shown in this May 22, 2005 picture. (Reuters)

A horse eats grass at Ruo'ergai grassland in Ruo'ergai County, China's southwestern Sichuan province, August 15,2006. (Reuters)

A man stands on a hill during sunset in Vina del Mar city ,about 75 miles (120 km) northwest of Santiago, August 11, 2007. (Reuters)

Mounds of salt formed by miners sit on the Salar de Uyuni, the world's biggest salt desert, where until recently mining salt was the only way to survive in this cold, arid corner of southwestern Bolivia, July 14, 2007. (Reuters)

People walk on a cliff overlooking Ram Plateau in the Nahanni National Park Reserve, Northwest Territories in this undated handout photo released June 9, 2009. (Reuters)

Concrete pylons stick out of the water at the Three Gorges Dam located northwest of Yichang city in Hubei Province, central China November 6, 2007. (Reuters)

A palm tree grows in the Errachidia reservoir near the Ziz oasis March 7, 2009. (Reuters)

A tourist makes a path in the snow on a ridge, some 3,200 metres (10,499 feet) above sea level, in the mountains outside Almaty February 1, 2009. (Reuters)