In this February 22, 2018 photo, a couple looks at a bag made out of Venezuelan Bolivars in La Parada, Colombia, on the border with Venezuela. Each collector item produced by Richard Segovia, sitting at the table, fetches between $10 and $15 – a huge markup from the pennies that bolivars retrieve on Venezuela's black market. (Photo by Fernando Vergara/AP Photo)

Small transportation boats, known as bumboats, leave trails of light as they travel across Marina Bay past the skyline of Singapore in this photo taken in 2004. Singapore holds a Jubilee weekend from 7 to 10 August to celebrate the 50th anniversary of its independence. Fifty years ago, hundreds of small boats lined the Singapore river in the city centre. Today, most small boats are gone, except a handful of neon-lit tourist ferries. Maritime trade is still the backbone of the city-state but after decades of rapid growth Singapore, which at less than half the size of London is among the world’s most densely populated nations, is also a popular tourist destination and a thriving global financial hub. (Photo by Edgar Su/Reuters)

“Diver in Magic Kingdom”. Green Lake (Grüner See) is located Tragöss Austria. In spring snowmelt raises the lake level about 10 meters. This phenomenon, which lasts only a few weeks covering the hiking trails, meadows, trees. The result is magical to watch diving landscapes. Photo location: Grüner See at Tragöss, Austria. (Photo and caption by Marc Henauer/National Geographic Photo Contest)

The rotating updraft base of a supercell thunderstorm, and a rear flank downdraft containing rain and hail, backlit by the setting sun, on May 10, 2014, in Climax, Kansas, United States. To most of us, dark clouds on the horizon usually means rain – but here in Kansas, they can also signal the start of a supercell. The huge formations, also known as rotating thunderstorms, are among the most powerful weather phenomenon found over land. They can occur anywhere where the conditions are right, but are normally found in more arid climates. These awe-inspiring supercells were captured south of Climax city by storm chaser Stephen Locke. (Photo by Stephen Locke/Barcroft Media)

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 chariot of God Bhairab is pulled through the city centre of Bhaktapur near Kathmandu during the Bisket festival April 10, 2015. The festival, which runs for more than a week and coincides with the Nepalese New Year, involves devotees offering prayers and the pulling of two chariots, one carrying the idol of God Bhairab and the other with the idol of Goddess Bhadrakali, around the ancient city of Bhaktapur. Devotees participate in the festival with the belief that they will be blessed with good health, fortune and harvest for the coming year. (Photo by Navesh Chitrakar/Reuters)

Chinese models with animal-themed body paintings pose during a campaign for animal protection at Sanya Color Zoo in Sanya city, south China's Hainan province, 10 January 2016. The girls wearing strapless bras and short pants only were colored with animal-themed paintings such as zebra, cheetah, tiger and peacock. They paraded throughout the newly-opened Sanya Color Zoo and met visitors to take pictures, causing envies from netizens living in north China who are suffering chills. (Photo by Imaginechina/Splash News)

Frander Arroyo, select wings of butterflies at Blue Morpho Butterfly House in Alajuela, Costa Rica, March 10, 2016. According to Arroyo, owner of Blue Morpho Butterfly House, he collects dead butterflies from his garden to mount as handicraft like earrings, necklaces, paintings and rings for export with prices ranging from $12 to $16 a piece. (Photo by Juan Carlos Ulate/Reuters)