Among the fish populations that could be harmed by the Xayaburi dam in Laos is the critically endangered Mekong giant catfish, considered by the Guinness Book of World Records to be the world’s largest freshwater fish. The fish, which grows to 650 pounds and about 10 feet long, is only found in the Mekong River. It is migratory, moving between downstream habitats in Cambodia upstream to northern Thailand and Laos each year to spawn. Some experts fear the Xayaburi dam could block the migration and drive the giant catfish to extinction. (Photo by Courtesy of Zeb Hogan/University of Nevada, Reno)

“The Victoria Falls or Mosi-oa-Tunya is a waterfall located in southern Africa on the Zambezi River between the countries of Zambia and Zimbabwe. A famous feature is a naturally formed pool known as the Devil's Pool, near the edge of the falls, accessed via Livingstone Island in Zambia. When the river flow is at a certain level, usually during the months of September to December, a rock barrier forms a pool with little current; some people swim in the pool. Occasional deaths have been reported when people slip over the edge of the rock barrier”. – Wikipedia

Photo: Devil's Pool – Victoria Falls, Zambia. (Photo by Siena College Study Abroad)

Take a look at this stunning photo of Tolbachik, an active volcanic complex on the Kamchatka Peninsula in far eastern Russia. Lava fountains and rivers ran through the area for months after the eruption began with the opening of two Tolbachik fissures in November of 2012. In the midst of this activity, photographers Luda and Andrey (lusika33) took a trip down to see that stunning hell valley on earth. (Photo by lusika33)

Rowers enter in Canaregio river during the 42nd Venice Vogalonga on May 15, 2016 in Venice, Italy. 42 years ago a group of Venetians, both amateur and professional rowers, came up with an idea of non-competitive race in which any kind of rowing boat can take part. The first Vogalonga began with the message to protest against the growing use of powerboats in Venice and the swell damage they do to the historic city. (Photo by Awakening/Getty Images)

Long-tailed mayflies (Palingenia longicauda) mate on the surface of the Tisza river near Tiszakurt, Hungary, June 14, 2016. Millions of these short-lived mayflies engage in a frantic rush to mate and reproduce before they perish in just a few hours during “Tiszaviragzas” or Tisza blooming season from late spring to early summer every year. (Photo by Laszlo Balogh/Reuters)

People in ethnic costumes jump over a bonfire during Ivan Kupala Day celebrations held by the Pripyat River in the town of Turauin Gomel Region, Belarus on July 6, 2020. Ivan Kupala Day, also known as Ivana-Kupala or Kupala Night, is a traditional pagan holiday celebrated in eastern Slavic cultures. Various rituals are traditionally performed on Kupala Night, including making flower wreaths, fortune-telling, jumping over bonfires, and burning a wheel-like effigy symbolizing the sun. (Photo by Natalia Fedosenko/TASS)

An employee of Paris city Hall removes padlocks clipped by lovers on the fence of the Pont des Arts over the River Seine in Paris, December 9, 2014. For years, visiting couples have hung brass padlocks on the iron grills lining the city's bridges to symbolise their undying love – they write their names on the locks, then toss the key into the Seine below. About 700,000 love locks are added every few months and Paris officials say they are damaging the bridges and threatening safety because of the added weight. (Photo by Philippe Wojazer/Reuters)

Snorkelers interact with a Florida Manatee inside of the Three Sisters Springs in Crystal River, Florida January 15, 2015. On winter days, Florida manatees flock by the hundreds to the balmy waters of Three Sisters Springs, drawing crowds of snorkelers and kayakers to the U.S. sanctuary, where people may swim with the endangered species. But as tolerant as the gentle, whiskered sea giants can be of the accidental kicks and splashes of delighted tourists, wild life regulators want to ban most canoes and paddle boards and create people-free zones to protect the wintering “sea cow”. Proposed limitations for this winter are awaiting approval by the U.S. Fish and Wildlife Service. (Photo by Scott Audette/Reuters)