Leanna Arcila, 7, is licked by Watson, a therapy dog with the Pawtucket police department, as she receives her COVID-19 vaccination from Dr. Eugenio Fernandez at Nathanael Greene Elementary School in Pawtucket, R.I., Tuesday, December 7, 2021. Even as the U.S. reaches a COVID-19 milestone of roughly 200 million fully-vaccinated people, infections and hospitalizations are spiking, including in highly-vaccinated pockets of the country like New England. (Photo by David Goldman/AP Photo)

These stunning pictures show a normally vicious tiger calmly swimming in a pool of algae, on Jule 9, 2014. The powerful cat takes a refreshing break by taking a dip in the bright green algae. But it looks like this big cat is scared of getting his head wet as he strains to keep it above the water. After splashing around for a bit the tiger gets out and tries to air-dry with specks of the vegetation dripping off his fur. The striking pictures were taken at Copenhagen zoo by snapper Soren Lundgren Neilson. (Photo by Soren Nielsen/Caters News)

A newly-hatched baby sea turtle makes its way into the Mediterranean Sea for the first time, as part of the Israeli Sea Turtle Rescue Center's conservation program, at a beach near Mikhmoret north of Tel Aviv, Israel September 9, 2019. Green turtles are endangered worldwide, the World Wildlife Fund says. Among other hazards, they are threatened by hunting, human encroachment on the beaches where they nest, and pollution of their feeding grounds offshore. According to the Israeli rescue center, only about 20 female green turtles nest along the Israeli Mediterranean coast during a breeding season that usually lasts from May until August. (Photo by Amir Cohen/Reuters)

A visiter is attracted by the chairs covered with solar panels at the factory of Yingli Green Energy Holding Company, also known as Yingli Solar, on June 20, 2011 in Baoding city of Hebei Province, China. According to a report by the International Energy Agency (IEA), China overtook America as the world' s largest energy consumer in 2010. New energy industries are becoming even more important than in the past. (Photo by Feng Li/Getty Images)

“Filthy Luker is a painter who is really attacking his audience. Who could think that a green octopus suddenly starts to creep out from the windows, a huge banana rind lounges just in the center of a road and the trees start to see!” (Photo by Filthy Luker/Vedi tutte le foto via Giornalettismo.com)

In this June 29, 2016 file photo, boats docked at Central Marine in Stuart, Fla., are surrounded by blue green algae. The 153-mile-long Indian River Lagoon has been plagued by harmful algae blooms. Water quality testing data analyzed by the AP showed the average phosphorous level – a byproduct of fertilizers and human waste that algae thrive on, rose nearly 75 percent between 2000 and 2016. (Photo by Greg Lovett/The Palm Beach Post via AP Photo)

Ngorongoro Crater (Tanzania). At 610m deep and 260 sq km, this is the largest unflooded caldera in the world. A blue-green vision from above it's a haven for engangered wildlife and Maasai livestock. The crater was formed three million years ago when a giant volcano, which could have been as high as Kilimanjaro, exploded and collapsed. The caldera formed the concentric fractures in the crust cracked down to a magma reservoir deep underground. (Photo by John Bryant/Getty Images)

“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)