Employees of the Park Royal resort wait for a shuttle to take them to work early in the morning on April 2, 2015 in Acapulco, Mexico. Despite problems with cartel violence Semana Santa is one of the biggest tourist weeks of the year in Acapulco, a city whose entire economy depends on tourism, and officials expect around 350,000 mostly Mexican visitors this week. (Photo by Jonathan Levinson/The Washington Post)

A women wearing a mask to protect from extreme smog visits the Tiananmen Gate in Beijing December 8, 2015 as China's capital issues its first ever "red alert" for pollution. (Photo by Damir Sagolj/Reuters)

Two revelers dressed as toy soldiers gesture toward a police officer in a patrol car during the traditional carnival parade in Wuerzburg, Germany, 15 February 2015. Under the motto “Carnival Parade is cool” about 160 groups with over 3,000 members took part in one of the biggest carnival parades in southern Germany. (Photo by Daniel Karmann/EPA)

A model jumps during a photo shooting, in Milan, Italy, Friday, January 15, 2016. Men's fashion week starts today and will run until Tuesday, January 19. (Photo by Luca Bruno/AP Photo)

Cave Diver, Anhumas Abyss, Bonito, Brazil: The Anhumas Abyss is an underground cavern with a crystal-clear lake below, more than 260 feet (79 m) deep. A visitor must enter through a narrow opening at the top of the chamber and rappel into the cave. Snorkeling and scuba diving in the lake reveal amazing scenery. Distinctive, conical limestone stalagmites and stalactites occupy the lake and the surrounding area, some reaching 65 feet (20 m) high. (Photo by Marcio Cabral/Nature’s Best Photography Awards 2017)

Shoppers walk past crocodiles for sale at a market in Bata on February 3, 2015. Markets in Equatorial Guinea sell a variety of animals including pangolins, monkeys and crocodiles as food. (Photo by Carl de Souza/AFP Photo)

Soldier boys at Fort Dix, N.J., learn something about guns during their working hours, as they show their girlfriends at a camp dance, December 13, 1940. In front row, playing with the coin amusement gun, from left: Pvt. Tom D'Amato of West Orange; Rose Sinkewicz, behind gun site, of Trenton; Julia Ivans of Trenton, and Pvt. Vernon Landers of Kearney. Back row: Pvts. William Sargent and William Corlies of Philadelphia. (Photo by AP Photo)

Visitors take photos of the fluorescent sea in the waters of Paishi Village, Dalian City, Liaoning Province, China, May 24, 2020, from the night of May 24 to the early morning of May 25, 2020. The fluorescent sea in dalian is caused by noctilucent algae in the sea water. (Photo by Costfoto/Barcroft Media via Getty Images)