Jan Kara (R) and Jan Holan pedal their boat, made with plastic bottles, on the Elbe river near Kostelec nad Labem July 15, 2014. Jan Kara, a 22-year-old student, and Jakub Bures, a 22-year-old car mechanic, built the 10-metre (32.8-feet) long boat from 5000 plastic bottles strapped to a wooden frame. (Photo by David W. Cerny/Reuters)

Participant wearing medieval costumes perform during an annual re-enactment of a battle near the village of Libusin, Czech Republic, April 23, 2016. About 2000 enthusiasts have come to simulate the medieval battle during the 24rd annual swordsmen gathering in Libusin village. (Photo by David W. Cerny/Reuters)

The Mercedes Vision EQ Silver Arrow is displayed at the Auto show in Paris, France, Tuesday, October 2, 2018, 2018. The one-seater vehicle is an homage to the record-breaking W 125 car from 1937. (Photo by Thibault Camus/AP Photo)

Rajesh Babu, a police officer, wearing a helmet depicting coronavirus, requests a commuter to stay at home during a 21-day nationwide lockdown to limit the spreading of coronavirus disease (COVID-19), in Chennai, India, March 28, 2020. (Photo by P. Ravikumar/Reuters)

A World War II era P-51 Mustang fighter plane stands in front of a modern 747-8 freighter and a 757 passenger jet at The Boeing Company's centennial celebration in Renton, Washington, U.S. July 15, 2016. (Photo by Alwyn Scott/Reuters)

A child looks at a polar bear swimming under a water in its enclosure on a hot summer day at Prague Zoo, Czech Republic, July 30, 2015. (Photo by David W. Cerny/Reuters)

Participants wearing medieval costumes re-enact the 1620 battle of Bila Hora between Bohemian Estates and Austrian Imperial with Catholic forces in Prague, Czech Republic September 18, 2016. (Photo by David W. Cerny/Reuters)

View of an American marine as he lies in a foxhole and whistles at a husky, one of the scouting dogs used during the landing on Guam, August 1944. (Photo by W. Eugene Smith/Time & Life Pictures/Getty Images)