A red deer stag takes a mud bath in Wollaton Park near Nottingham, England on May 23, 2020. Gareth Williams, who took the photograph, said it was a “once in a lifetime shot”. (Photo by Gareth Williams/Kennedy News)

Located in East Java, Indonesia, Kawah Ijen is a volcano is home to the largest acidic crater lake in the world. What turns the waters of the lake in the 1 km caldera its beautiful turquoise color are the highly sulfuric gases emitted from the volcano underneath.

Two Red Deer stags stand in the early morning mist in Richmond Park on October 15, 2011 in London, England. Autumn sees the start of the “Rutting” season where the large Red Deer stags can be heard roaring and barking in an attempt to attract females known as bucks. The larger males can also be seen clashing antlers with rival males. (Photo by Dan Kitwood/Getty Images)

A red deer stag in Bushy Park, southwest London, pulls a comical face for the camera in the second decade of November 2023. (Photo by Andrew Wood/Caters News Agency)

A group of stags charge across a frosty field in Bushy Park, London, leaping in near-perfect formation as the early morning mist hangs low in the second decade of December 2025. (Photo by Max Ellis/The Times)

Rob, a British man in his late 20's in Magaluf, Majorca on his stag party, kisses a participant in a wet t-shirt competition hosted at Mambo's Terrace on June 28, 2013. (Photo by Peter Dench/Getty Images Reportage)

A red deer looks as though it is yawning while it bellows at sunrise. The stag created a cloud of steamy breath as it was warmed by the first light of the sun in Richmond Park, London on October 28, 2025. (Photo by Cristian Vasile/Solent News & Photo Agency)

“Contrails (short for “condensation trails”) or vapour trails are artificial clouds that are the visible trails of condensed water vapour made by the exhaust of aircraft engines. As the hot exhaust gases cool in the surrounding air they may precipitate a cloud of microscopic water droplets or, if the air is cold enough, tiny ice crystals”. – Wikipedia

Photo: An airplane leaves a vapor trail as it flies in front of he moon on January 17, 2007 above Hanover, Germany. (Photo by Alexander Hassenstein/Getty Images)