Young Ian Archibald ponders the consequences of a complex critical study of beauty contestants during the Miss TV Times finals in London. (Photo by Central Press/Getty Images). 30 July 1971

“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)

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)

Two sailors from HMS Fury enjoy a smoke with two women in bathing suits on a beach in Jersey, where their ship is on a visit. (Photo by William Vanderson/Fox Photos/Getty Images). 29th June 1935

Gulparai, 12, (L) smokes heroin along side her mother Sabera and brother Zaher, 14, (R) August 27, 2007 in Kabul, Afghanistan. (Photo by Paula Bronstein/Getty Images)

Three secondary schoolboys smoking an illicit cigarette in Hyde Park, London. (Photo by Evening Standard/Getty Images). May 1972

Iraqi Kurdish female fighter Haseba Nauzad looks through a pair of binoculars during a deployment near the frontline of the fight against Islamic State militants in Nawaran near Mosul, Iraq, April 20, 2016. (Photo by Ahmed Jadallah/Reuters)