View of the “Sunset Lake” hot spring with it's unique colors caused by brown, orange and yellow algae-like bacteria called Thermophiles, that thrive in the cooling water turning the vivid aqua-blues to a murkier greenish brown, in the Yellowstone National Park, Wyoming on June 1, 2011. Yellowstone National Park, was established by the U.S. Congress and signed into law by President Grant on March 1, 1872. The park is located primarily in the U.S. state of Wyoming, though it also extends into Montana and Idaho and was the first national park in the world. It is known for its wildlife and its many geothermal features, especially the Old Faithful Geyser. (Photo by Mark Ralston/AFP Photo)

A DC-10 air tanker delivers flame retardant to the Blue Cut fire in Wrightwood, Calif., Wednesday, August 17, 2016. A wildfire with a ferocity never seen before by veteran California firefighters raced up and down canyon hillsides, instantly engulfing homes and forcing thousands of people to flee, some running for their lives just ahead of the flames. (Photo by Alex Gallardo/AP Photo)

Models pose in designs from May Quant's collection on a street in London, England, on October 16, 1969. Grania, left, wears the "Shimmy Shimmy," a white rayon dress over matching pants with a shawl. Baba, center, wears "Razzamatazz," a jumpsuit featuring plastic sequins in blue, silver and red on nylon. Linda wears "Muffit," a pink minidress with an old English style floppy mobcap. (Photo by AP Photo)

“The Red-eyed Treefrog (Agalychnis callidryas) is an arboreal hylid native to Neotropical rainforests in Central America. Red-eyed tree frogs, as their name states, have red eyes with vertically narrowed noses, a vibrant green body with yellow and blue vertically striped sides, and orange or yellow webbed feet and toes”. – Wikipedia. (Photo by Donald Quintana)

Visitors enjoy watching the Blue Nemophila flowers bloom during the Golden Week holidays, at Hitachinaka Kaihin Park on May 02, 2010 in Hitachinaka, Ibaraki, Japan. Millions of nemophilas blossom across the “Miharashi No Oka” hill at Hitachi Seaside Park for the annual “Nemophila Harmony” flower festival. (Photo by Koichi Kamoshida/Getty Images)

Brave photographer Masa Ushioda captured the shots of this wild gator in vast marsh land in the Everglades National Park, in Florida, USA. He said: “Bright sunlight and blue sky were critical elements in this picture – in addition to getting a wild 10-foot alligator in the middle of the viewfinder with a perfect angle”.

Photographer Andy Hall joins the thousands of fans from west Africa who have gathered for Baaba Maal's annual Blues du Fleuve festival in Senegal. Here: Dancers wait to perform on stage. (Photo by Andy Hall/The Observer)