People immerse themselves in an ice hole in the Chulym river, with the air temperature at about minus 12 degrees Celsius (10.4 degrees Fahrenheit), during celebrations for the Russian Orthodox Epiphany outside of the town of Nazarovo, Krasnoyarsk region January 19, 2015. (Photo by Ilya Naymushin/Reuters)

Bangladeshi relatives wail near bodies of victims after a river ferry carrying about 100 passengers capsized Sunday after being hit by a cargo vessel,in Manikganj district, about 40 kilometers (25 miles) northwest of Dhaka, Bangladesh, Sunday, February 22, 2015. (Photo by A. M. Ahad/AP Photo)

Central Bangkok and the Chao Phraya River are seen from an abandoned skyscraper in Bangkok April 19, 2015. The abandoned building, known as Satorn Unique, dubbed the “ghost tower” was destined to become one of Bangkok's most luxurious residential addresses but construction was never completed as the Thai economy was hit during the 1997 Asian Financial Crisis. Now, many travellers visit and explore 49-storey skyscraper. (Photo by Athit Perawongmetha/Reuters)

A man (2nd L) takes pictures as visitors run away from a wave caused by a tidal bore which surged past a barrier on the banks of Qiantang River, in Hangzhou, Zhejiang province August 14, 2014. (Photo by Reuters/Stringer)

Jan Kara (R) and Jan Holan pedal their boat, made with plastic bottles, on the Elbe river near Kostelec nad Labem July 15, 2014. Jan Kara, a 22-year-old student, and Jakub Bures, a 22-year-old car mechanic, built the 10-metre (32.8-feet) long boat from 5000 plastic bottles strapped to a wooden frame. (Photo by David W. Cerny/Reuters)

Widows, who have been abandoned by their families, light sparklers after offering prayers on the banks of the river Yamuna as part of Diwali celebrations organised by non-governmental organisation Sulabh International in Vrindavan, Uttar Pradesh October 21, 2014. (Photo by Ahmad Masood/Reuters)

A general view of dried-up rivers in the Pilbara region of Western Australia December 2, 2013. Western Australia's Pilbara region, which is the size of Spain, has the world's largest known deposits of iron ore and supplies nearly 45 percent of global trade in the mineral. (Photo by David Gray/Reuters)

National Geographic photographer Steve Winter has spent most of his adult life shooting wild cats. Photo: A 14-month-old cub, cooling off in a pond, is riveted by a deer that appeared near the shore. Tigers are powerful swimmers; they can easily cross rivers four to five miles wide and have been known to swim distances of up to 18 miles. (Photo by Steve Winter/National Geographic)