A giant river otter, the world's largest otter species, looks out of its enclosure at the newly completed River Safari in Singapore, on March 25, 2013. (Photo by Wong Maye-E/Associated Press)

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)

Men rest on a boat in the overflowed Ganges River under the Shastri Bridge in Allahabad on August 17, 2022, as water levels of the Ganges and Yamuna rivers rose following monsoon rainfalls. (Photo by Sanjay Kanojia/AFP Photo)

People wade through a flooded path near Sangam, the confluence of the Ganges, Yamuna and mythical Saraswati rivers after the water level of river Ganges and river Yamuna rose, in Allahabad on October 14, 2022. (Photo by Sanjay Kanojia/AFP Photo)

Dancers pose for a photo as they prepare during Festival Cilung or “Love the Environment” Festival, where boats made from recycled materials, mostly plastic bottles, sail on the Ciliwung River, one of the most polluted rivers in the world, to raise public awareness about river pollution, in Jakarta, Indonesia, on September 28, 2025. (Photo by Willy Kurniawan/Reuters)

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 Hindu devotee drinks water from the Ganges River at the Sangam area, the confluence of rivers Ganges, Yamuna, and the mythical Saraswati, in Allahabad on March 16, 2021. (Photo by Sanjay Kanojia/AFP Photo)

A river otter (lontra longicaudis) of 6-weeks-old looks in the mirror during a bath in the Animal Welfare Unit of the Zoo in Cali, Colombia, on October 22, 2019. The baby otter was found abandoned brought to the Cali Zoo for breeding, for its extensive experience in raising these species. According to the International Union for Conservation of Nature the river otter (lontra longicaudis) are in danger of extinction, because of mining, agriculture, pollution of rivers and housing construction in their habitat. (Photo by Luis Robayo/AFP Photo)