Blue, white and red brassieres, the colours of the French national flag, hang from a balcony in Marseille, France, November 27, 2015 as the French President called on all French citizens to hang the tricolour national flag from their windows on Friday to pay tribute to the victims of the Paris attacks during a national day of homage. (Photo by Jean-Paul Pelissier/Reuters)

A man and a dog bathe in a fountain during celebrations of Paratroopers' Day in Moscow' s Gorky Park on August 2, 2017. Russia' s Airborne Troops (Blue Berets) celebrate their professional holiday on the Day of Elijah the Prophet, their Patron. (Photo by Stanislav Krasilnikov/TASS)

David Bowie wears an eyepatch in red suit and guitar on blue background at Top Pop television studios in Holland while doing playback to his hit song Rebel Rebel in 1974. (Photo by Barry Schultz/Sunshine/REX Shutterstock)

American model Lori Harvey attends the Tiffany & Co. Celebration of the launch of Blue Book 2024: Tiffany Céleste at The Beverly Estate on April 25, 2024 in Beverly Hills, California. (Photo by Stefanie Keenan/Getty Images for Tiffany & Co.)

Boozed-out revellers donned fancy dress as they welcomed in the Bank Holiday at the Otley Run. Hundreds swarmed Leeds, UK on Saturday, March 30, 2024, as the infamous tipple mission got underway beneath blue skies and sunshine. (Photo by NB Press LTD)

“Kissing Booth” star Joey King (in blue wig) and “Game of Thrones” alum Maisie Williams laugh it up while enjoying a night on the town full of shots and karaoke in the second decade of September 2025. (Photo by Joey King/Instagram)

Kia Vue of St. Paul sports long nails at the Minnesota Hmong New Year celebration Saturday, November 29, 2014, at the Saint Paul RiverCentre in St. Paul, MN. The annual Minnesota Hmong New Year celebration will be held at the Saint Paul RiverCentre November 28–30. Hmong New Year has a deep cultural significance to the Hmong community. It is a celebration of accomplishments during the past year and a time to welcome a new beginning. (Photo by David Joles/Star Tribune)

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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).