A couple covered in mud wait for it to dry at the Salt-works lakes near the Black Sea town of Burgas in Bulgaria on July 25, 2019. Thousands of tourists visit the red salt lakes for mud baths, which are believed to help the healing of muscular disorders and rheumatism. (Photo by Nikolay Doychinov/AFP Photo)

Pakistani boys jump in the water to cool off in a pond to beat the heat wave continues in Larkana, Pakistan, 26 June 2021. Pakistan's Meteorological Department (PMD) said the weather in the city will remain hot and humid for the next three days. (Photo by Waqar Hussain/EPA/EFE)

Students run out of their school celebrating their high school graduation at Nacka Gymnasium following the spread of the corona virus disease (COVID-19) in Stockholm, Sweden, June 3, 2020. (Photo by Jessica Gow/TT News Agency via Reuters)

Performers ride atop a car leading to the the National Circus Day celebration in Santiago, Chile, Saturday, September 4, 2021, amid the new coronavirus pandemic. Chile's Culture Minister set the stage for the first circus performances with a ringside public since the beginning of the pandemic quarantine measures as the South American country looks to fully roll back almost all COVID-19 related restrictions. (Photo by Esteban Felix/AP Photo)

Visitors to Kensington Gardens are reflected in Anish Kapoor's sculpture “C-Curve 2007” on September 27, 2010 in London, England. (Photo by Peter Macdiarmid/Getty Images)

A Republican farmer defending a farm on the outskirts of Irun against Nationalist forces during the Spanish Civil War, 6th September 1936. A comrade lies dead by his side. (Photo by Keystone/Hulton Archive/Getty Images)

Blanka Vlasic of Croatia and Team Europe celebrates a clearance in the women's high jump during the IAAF/VTB Continental Cup at the Stadion Poljud on September 5, 2010 in Split, Croatia. (Photo by Michael Steele/Getty Images)

Tokio Hotel fan Jennifer poses with Bill Kaulitz wax figure at Madame Tussauds on September 30, 2008 in Berlin, Germany. (Photo by Florian Seefried/Getty Images)