These photographs of hundreds of ducks following their leader down a river are truly mesmerizing. Rafeur Rahman of Bangladesh climbed a high bridge and saw hundreds of ducks apparently playing a game of follow the leader. More than 500 ducks live on the river, where the mosses and snails provide the perfect habitat. Here: Ducks in the river Baral in Bangladesh. (Photo by Rafeur Rahman/Caters News Agency)

Staff of a boat restaurant on the Taedong River line up at the entrance as they wait to greet customers Sunday, June 18, 2017, in Pyongyang, North Korea. The boat is berthed along the river, which is the fifth longest river on the Korean Peninsula and runs through the country's capital, Pyongyang. (Photo by Wong Maye-E/AP Photo)

A monkey drinks water from a tap on a hot afternoon in Jammu, the winter capital Kashmir, India, 17 May 2016. Temperatures of around 42 degrees Celsius were forecast in the region. According to the news reports the Indian government decided to divert water by its river interlinking plans from rivers like Brahmaputra and the Ganges towards those rivers facing the drought likesituation . Many Indian states have been affected by drought and have been hit hard by water scarcity. (Photo by Jaipal Singh/EPA)

Growing cities, overuse of fertilizers and factory wastewater have degraded China's water supplies to the extent that half the nation's rivers and lakes are severely polluted. China aims to spend $850 billion to improve filthy water supplies over the next decade, but even such huge outlays may do little to reverse damage caused by decades of pollution and overuse in Beijing's push for rapid economic growth. Photo: Fishermen row a boat in the algae-filled Chaohu Lake in Hefei, Anhui province, June 19, 2009. (Photo by Jianan Yu/Reuters)

In this July 29, 2021 file photo, the pillars of the massive Rosario-Victoria Bridge are exposed during a drought affecting the Parana River near Rosario, Argentina. At the port city of Santa Fe the river registered a level of 22 centimeters, the lowest in 50 years. (Photo by Victor Caivano/AP Photo/File)

Tim Anderson final balanced rock stack in the Llano River. Tim Anderson, rock balancing “pro” from Pennsylvania, carefully worked to balance his stack on a dry spot in the Llano river Saturday March 12, 2016. He was an honored guest of the festival and enjoyed visiting Texas so he came for another year. The river was higher this year because of the rains so the balancers could not get to the better rock that were available last year. (Photo by Nell Carroll/American-Statesman)

A participant from Indonesia waits to perform a dance during the last day of World Culture Festival on the banks of the river Yamuna in New Delhi, India, March 13, 2016. The festival opened on the banks of the Yamuna River in the Indian capital Friday despite concerns the sprawling construction of roads, ramps and pontoon bridges would irreparably damage the river's floodplains. (Photo by Adnan Abidi/Reuters)