The Y-40 Deep Joy is the worlds deepest pool. Y-40 is projected by Architect Emanuele Boaretto and supported by the “Boaretto Group Hotel and Resort”. The name Y-40 is inspired by mathematical symbols. “Y” is the ordinate axis of the Cartesian system and “–40” means the world's record depth or our pool- that is 40 meters underground. (Photo by Courtesy Y40 Deep Joy)

In this photo taken Tuesday, October 14, 2014, skulls and bones are stacked at the Catacombs in Paris, France. The subterranean tunnels, stretching 2 kilometers (1.24 miles), cradle the bones of some 6 million Parisians from centuries past and once gave refuge to smugglers. The site used to close at 5 p.m., but is now staying open until 8 p.m. The change is mainly aimed at allowing more people to visit and reducing long lines, since it can only hold a limited number of people at a time and visits can't be reserved in advance. (Photo by Francois Mori/AP Photo)

A graffiti, portraying a woman, is seen in Medellin, Colombia on November 19, 2017. Mural graffitis from different artists, street art can be seen in almost every city on Earth, but street arts raw power and potential for change was felt by me most intensively in Medellins Comuna 13, previously one of Colombias most dangerous neighbourhoods, in fact Communa 13 was constant battleground between gangs, narcos, paramilitaries and the government, but today you would hardly recognise it. (Photo by Juancho Torres/Anadolu Agency/Getty Images)

A woman sticks out her tongue as she shops at the Quinta Crespo street market in downtown Caracas, Venezuela, Saturday, January 26, 2019. The country's political showdown moves to the United Nations Saturday where a Security Council meeting called by the United States will pit backers of President Nicolas Maduro against the Trump administration and supporters of the country's self-declared interim leader Juan Guaido. (Photo by Rodrigo Abd/AP Photo)

Children wearing cardboard lion dance masks walk along a street in Beijing on January 13, 2023. China has announced its first overall population decline in recent years amid an aging society and plunging birthrate. (Photo by Mark Schiefelbein/AP Photo)

People are seen through a window as they attend the traditional wedding ceremony of Emir's 7 children in Abuja, Nigeria, December 26, 2020. (Photo by Afolabi Sotunde/Reuters)

Police officers clear the area near Borough market at London Bridge on June 3, 2017 in London, England. Police have responded to reports of a van hitting pedestrians on London Bridge in central London. (Photo by Dan Kitwood/Getty Images)

A health official checks the body temperature of a burqa-clad woman passenger amid concerns over the spread of the COVID-19 novel coronavirus at the Lahore Railway station in Lahore on March 19, 2020. (Photo by Arif Ali/AFP Photo)