A French riot police officer is surrounded by flames, during a demonstration against the controversial labour reforms of the French government in Paris on September 15, 2016. Opponents of France's controversial labour reforms took to the streets on September 15, 2016 for the 14th time in six months in a last-ditch bid to quash the measures that lost the Socialist government crucial support on the left. Scores of flights in and out of France were cancelled as air traffic controllers went on strike to try to force the government to repeal the changes that became law in July. (Photo by Thomas Samson/AFP Photo)

A face mask is placed on one of the 'Three business men who brought lunch' statues on Swanston street on March 29, 2020 in Melbourne, Australia. All international arrivals into Australia from midnight on Saturday will be placed into mandatory quarantine in hotels for 14 days as the Federal Government increases restrictions to stop the spread of COVID-19. (Photo by Asanka Ratnayake/Getty Images)

In this February 22, 2021, file photo, climate activist Disha Ravi, 22, travels in a car as she is taken to a court in New Delhi, India. To her friends, Ravi, was most concerned about her future in a world where temperatures are rising. But her life changed last month as she became a household name in the country, dominating news coverage after police charged her with sedition, a colonial-era law which carries a sentence up to life. Her alleged crime: sharing an online document to help amplify months-long farmer protests in India on Twitter. She was released after 10 days in custody. (Photo by Dinesh Joshi/AP Photo/File)

Aurorae category runner-up: Lone Tree under a Scandinavian Aurora by Tom Archer (UK). The photographer decided to explore the area around the hotel on a very crisp -35C evening in Finnish Lapland. When he found this tree, he decided to wait for the misty conditions to change and could not believe his luck when the sky cleared and the aurora came out in the perfect spot. Archer spent about an hour photographing it before his camera started to lock up because of the harsh conditions, but by then he was happy to call it a night. (Photo by Tom Archer/2020 Astronomy Photographer of the Year)

Wide-angle category winner. Part of the Illusion by Marcus Blatchford (UK). Location: National Dive & Activity Centre, Chepstow, Wales. “This is the deepest inland dive centre in the UK. The dive plan was to explore the deep end, but this time I dived ‘unplugged’ (without my strobes). With the exception of this change to my camera technique, there were no planned shots I wanted to achieve – just a fun dive with ad-hoc photos along the way. Shortly after this photo was captured, in 6C water and two hours of decompression ahead of us, we turned and started the long ascent back to the surface”. (Photo by Marcus Blatchford/Underwater Photographer of the Year 2016)

Lido cabaret dancers perform during a demonstration outside the cabaret as dancers, other employees and union activists are gathering to try to save their jobs and the history of the cabaret, known for its dinner theater and its “Bluebell Girls” revue, Saturday, May 28, 2022 in Paris. Amid financial troubles and changing times, the venue's new corporate owner is ditching most of the Lido's staff and its high-kicking, high-glamour dance shows – which date back decades and inspired copycats from Las Vegas to Beirut – in favor of more modest musical revues. (Photo by Thomas Padilla/AP Photo)

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Lake Natron is a salt lake located in northern Tanzania, close to the Kenyan border, in the eastern branch of the East African Rift. The lake is fed by the Southern Ewaso Ng'iro River and also by mineral-rich hot springs. It is quite shallow, less than three meters (10 feet) deep, and varies in width depending on its water level, which changes due to high levels of evaporation, leaving concentrations of salt and other minerals, notably sodium carbonate (natron).