Opera singers perform in the pool “AquAria PALAOA” during a rehearsal at the swimming pool Neukoelln on April 27, 2011 in Berlin, Germany. The premiere of the underwater opera AquAria PALAOA is on May 1st. (Photo by Andreas Rentz/Getty Images)

Street fighting in Berlin between Government troops and Spartacists, during the Spartacist uprising which followed Germany's defeat in World War I. (Photo by Keystone/Getty Images). 1919

Egyptian President Hosni Mubarak speaks to the media after talks with German Chancellor Angela Merkel at the Chancellery on April 23, 2008 in Berlin, Germany. (Photo by Sean Gallup/Getty Images)

Hunting for a Salmon (more precisely – Oncorhynchus nerka). Scene of action: Kuril lake, Kamchatka, Russia. Action time: October – end of November, 2012. (Photo by Sergey Gorshkov)

“The Challenge!” Young boy relishes in a game of tug of war before school. Photo location: Lake Titicaca, Peru. (Photo and caption by Paul Heyman/National Geographic Photo Contest)

A tourist is seen at the Caka Salt Lake in Wulan County, northwest China's Qinghai Province, September 4, 2020. (Photo by Zhang Long/Xinhua News Agency)

Aerial view of a boat working in the green water of Taihu Lake covered by blue-green algae, Wuxi city, Jiangsu province, China on May 23, 2018. (Photo by Imaginechina/Rex Features/Shutterstock)

Paragliders fly towards the landing area of the “Acro Show” above Lake Geneva in Villeneuve, Switzerland on Sunday, August 26, 2018. (Photo by Valentin Flauraud/Keystone via AP Photo)