South Korean soldiers participate in a winter river crossing operation in preparation for a possible North Korean attack on February 8, 2012 in Yeoju, South Korea. The Korean peninsula is the world's last Cold War frontier as stalinist North Korea and pro-western South Korea have been technically at war since the 1950-53 conflict. (Photo by Chung Sung-Jun/Getty Images)

The Mike O'Callaghan–Pat Tillman Memorial Bridge is an arch bridge in the United States that spans the Colorado River between the states of Arizona and Nevada. The bridge is located within the Lake Mead National Recreation Area approximately 30 miles (48 km) southeast of Las Vegas, Nevada, and carries U.S. Route 93 over the Colorado River.

Water gushes out from the Xiaolangdi Reservoir on the Yellow River during a sand-washing operation on June 20, 2012 in Luoyang, China. The sand-washing operation, which started on June 19 and will last for about 20 days, is conducted to clear out the silt deposits at the dam. (Photo by China Foto Press)

“El rio mas bonito del Mundo”, the most beautiful river of the world, the “River of five colors”, the “Rainbow River”, or even the “Escaped from Paradise”, are the shimmering appellations that Colombians give to Cano Cristales, a small stream located in the heart of the Macarena National Park, 150 km (93 miles) south of Bogota. Photo: A waterfall is seen at the end of the rainy season, in August, when the water level finally decreases, in the Cano Cristales RIver in the Sierra de la Macarena in Colombia. It has become covered with a bright pink endemic aquatic plant, Macarenia Clavigera. (Photo by Olivier Grunewald)

A security exercise takes place along the River Thames on January 19, 2012 in London, England. The exercise including around 44 police officers, 94 military personnel, 15 boats and a Royal Navy Lynx helicopter was conducted by both the Metropolitan Police and the Royal Marines and designed to test their joint capability ahead of the 2012 London Olympic Games. (Photo by Dan Kitwood/Getty Images)

A boy swims in Chao Phraya River as he helps to place a Krathong, or a “floating basket”, in the water amid a yearly festival during which rafts of neatly folded banana leaves, decorated with flowers, candles and incense, are offered to thank the water goddess for good luck and for using her water to grow crops and support all life, in Bangkok, Thailand on November 8, 2022. (Photo by Chalinee Thirasupa/Reuters)

Cole Yeoman steps over a large crack along River Road, Avonside on February 25, 2011 in Christchurch, New Zealand. The death toll has risen to 113 and the hope for finding survivors is fading as rescuers search through debris for over 200 still missing following a 6.3 magnitude earthquake that struck Christchurch on Tuesday. The quake, which was an aftershock of a 7.1 magnitude quake that struck the South Island city on September 4, 2010, has seen damage and fatalities far exceeding those of the original. (Photo by Martin Hunter/Getty Images). CHRISTCHURCH, NEW ZEALAND – FEBRUARY 25

Imogen Bankier of Scotland (L) and Chris Adcock of England in action during their round one mixed doubles match in the Yonex All England Badminton Open Championship on March 9, 2011 in Birmingham, England.