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)

Tightrope walker Tatian-Mosio Bongonga hangs from a tightrope as she pauses while scaling the Monmartre hill towards the Sacre Coeur Basilica (not pictured) in Paris, France, July 20, 2018. (Photo by Philippe Wojazer/Reuters)

A surfer rides a wave as bioluminescent plankton lights up the surf around him during the coronavirus outbreak, Thursday, April 30, 2020, in Newport Beach, Calif. California Gov. Gavin Newsom on Thursday temporarily closed Orange County's coastline after large crowds were seen there. (Photo by Mark J. Terrill/AP Photo)

Protesters run for cover after riot police fired tear gas towards the bridge they were climbing down to the road below, to escape from Hong Kong Polytechnic University campus and from police, in Hung Hom district in Hong Kong on November 18, 2019. Dozens of Hong Kong protesters escaped a besieged university campus on November 18 by lowering themselves on a rope from a footbridge to a highway, AFP video showed. Once on the road they were seen being picked up by waiting motorcyclists. (Photo by Anthony Wallace/AFP Photo)

Steam rises from Lake Superior as the ship St. Clair comes to harbor during some of the coldest temps of the year, Sunday, December 31, 2017, at Canal Park in Duluth, Minn. The St. Clair is a self-unloader built in 1976 at Sturgeon Bay, Wis., and is 770 feet long and has 26 hatches that open into 5 cargo holds, providing a load capacity of 45,000 tons. (Photo by David Joles/Star Tribune via AP Photo)

In this Sunday, March 31, 2019, file photo, Marc Marquez, of Spain, drives his motorcycle during the Moto GP race at the Termas de Rio Hondo circuit in Argentina. The reigning MotoGP champion has dominated the Circuit of the Americas from the year it opened and the Repsol Honda rider comes back right back on top of the season standings in a chase for a sixth title in seven years. (Photo by Nicolas Aguilera/AP Photo/File)

A staff member demonstrates how she puts on the helmet of a mock space suit at the C-Space Project Mars simulation base in the Gobi Desert outside Jinchang, Gansu Province, China, April 17, 2019. The facility – comprising several interconnected modules including a greenhouse and a mock decompression chamber – opened its doors to the public. (Photo by Thomas Peter/Reuters)

Aymara indigenous women “Martha La Altena” (El Alto's Martha) (R) and “Susana La Bonita” (Pretty Susana) take part in a freestyle wrestling flight in El Alto, on June 29, 2018. “Cholita Fighters” aim to include their show in a tourist route. (Photo by Aizar Raldes/AFP Photo)