“Winter shapes, Moscow river”. Moscow river at this part is never covered by ice. When the temperature is very low it's possible to see a strong fog. Morning light and pipes of the oli factory creates a fantastic landscape. Photo location: Moscow, Russia. (Photo and caption by Sergey Rumyantsev/National Geographic Photo Contest)

“People of the River”. This is a Karo tribe family; father, mother, two sisters and two brothers. The tribe, who live along the Omo River in east Africa, incorporate rich symbolism into their rituals by using ornate body art, headdresses and body scarification to express beauty and significance. (Photo by Jatenipat Ketpradit/International Portrait Photographer of the Year)

Rick Sorenson, owner of the Rio Ramaza Marina, wades in the Sacramento River after securing an old paddlewheel boat on his property as the river makes its way up the levee on Garden Highway in Sacramento, Calif., Monday, January 9, 2017. (Photo by Hector Amezcua/The Sacramento Bee via AP Photo)

A house built on a rock on the river Drina is seen near the western Serbian town of Bajina Basta, about 160km (99 miles) from the capital Belgrade May 22, 2013. The house was built in 1968 by a group of young men who decided that the rock on the river was an ideal place for a tiny shelter, according to the house's co-owner, who was among those involved in its construction. (Photo by Marko Djurica/Reuters)

This brave swimmer certainly has a brrracing workout each weekend she skinny dips in one of the coldest rivers in Europe which regularly plummets to temperaturess of –9C. Inna Vladimirskaya, 32, strips off on the banks of the Dnieper river, in Kiev, Ukraine, every Sunday morning, and takes a swim after jogging along the snowy banks of the river in the nip. (Photo by David Tesinsky/Caters News Agency)

Fishermen jump into a small river to catch trout as they celebrate Fischertag (Fisherman's Day) in downtown Memmingen, southern Germany, July 25, 2015. The annual Fisherman's Day (Fischertag) tradition goes back to the year of 1465 where every fisherman who were born in Memmingen tries to catch trout from the river. The participant who catches the biggest trout will be named the “Fisher King” for one year. (Photo by Michaela Rehle/Reuters)

A Naga sadhu, or naked Hindu holy man, poses for a picture after taking a holy dip in the Godavari River during Kumbh Mela, or Pitcher Festival, at Trimbakeshwar in Nasik, India, Sunday, September 13, 2015. Hindus believe taking a dip in the waters of a holy river during the festival, will cleanse them of their sins. According to Hindu mythology, the Kumbh Mela celebrates the victory of gods over demons in a furious battle over a nectar that would give them immortality. (Photo by Rafiq Maqbool/AP Photo)

In this January 7, 2016, photo, conservationists of Borneo Orangutan Survival Foundation hold a baby orangutan rescued along with its mother during a rescue and release operation for orangutans trapped in a swath of jungle in Sungai Mangkutub, Central Kalimantan, Indonesia. Last year's forest fires drove orangutans closer to the river bank, where they had to live in an over-populated swath of forest as thin as 30 meters wide along the river. (Photo by Dita Alangkara/AP Photo)