A man wearing a hazmat suit and a mask holds a sign reading “The end is near – call grandma” at Times Square on March 14, 2020 in New York City. The World Health Organization said March 13, 2020 it was not yet possible to say when the COVID-19 pandemic, which has killed more than 5,000 people worldwide, will peak. “It's impossible for us to say when this will peak globally”, Maria Van Kerkhove, who heads the WHO's emerging diseases unit, told a virtual press conference, adding that “we hope that it is sooner rather than later”. (Photo by Johannes Eisele/AFP Photo)

A statue of a Japanese Akita dog named “Hachiko” wearing a face mask is seen near Shibuya Station Wednesday, April 8, 2020, in Tokyo. Japanese Prime Minister Shinzo Abe declared a state of emergency on Tuesday for Tokyo and six other prefectures to ramp up defenses against the spread of the new coronavirus. Hachiko has waited for his owner University of Tokyo Prof. Eizaburo Ueno at the same place by the station every afternoon, expecting him to return home for nearly 11 years even after Ueno's death at work. (Photo by Eugene Hoshiko/AP Photo)

South Korean performers participate in a re-enactment of the battle of the Korean war during the ceremony to mark the 70th anniversary of the Korean War in Cheorwon, near the border with North Korea on June 25, 2020 in Cheorwon, South Korea. Over 66,000 South Koreans have been separated from their families during the Korean War which started on June 25, 1950, and effectively split the Korean Peninsula into two over the 3-year conflict. (Photo by Chung Sung-Jun/Getty Images)

A youth poses while holding two fishes before his face in Iraq's southern port city of al-Faw, 90 kilometres south of Basra near the Shatt al-Arab and the Gulf, on May 18, 2020. In Iraq, a national lockdown to halt the COVID-19 coronavirus pandemic has found some unexpected fans: local businesses who no longer have to compete with Turkish, Iranian or Chinese imports. Those countries, as well as Saudi Arabia, Jordan and Kuwait, typically flood Iraqi markets with inexpensive products at prices local producers can't compete with. (Photo by Hussein Faleh/AFP Photo)

A cat looks on near the Victory Pillar at the ruins of the Serapeum of Alexandria, an ancient Greek temple dating to the Ptolemaic and Roman periods (246 BC – 391 AD) dedicated to the city's protector deity Serapis, in Egypt's northern coastal city of Alexandria on November 24, 2023. The giant Corinthian column, commonly misidentified as “Pompey's Pillar”, is a Roman triumphal column set up in honour of the Roman emperor Diocletian (298–302 AD), and originally supported a colossal porphyry statue of the emperor in armour. (Photo by Amir Makar/AFP Photo)

A woman lies injured after an incident on Westminster Bridge in London on Wednesday, March 22, 2017. A police officer has been stabbed near to the British Parliament and the alleged assailant shot by armed police. Scotland Yard report they have been called to an incident on Westminster Bridge where several people have been injured by a car. (Photo by Toby Melville/Reuters)

South Korean youths play Pokemon Go on July 15, 2016 in Sokcho, South Korea. South Korea is not one of the initial Pokemon Go released countries, nor is the game likely to be released officially any time soon as the South Korean government does not allow Google to use its map; however, South Korean game enthusiasts are now visiting a handful of loophole areas in the north eastern side of the country near the border of North Korea to join the global frenzy of Pokemon Go. (Photo by Jean Chung/Getty Images)

Son doong cave is a cave in Phong Nha-Kẻ Bàng National Park, Bố Trạch district, Quảng Bình Province, Vietnam. Currently the biggest known cave in the world, the cave is located near the Laos-Vietnam border. Inside is a large, fast-flowing underground river.
In early August 2013, the first tourist group explored the cave on a guided tour at a cost of US$3,000 each. The group had six members from Australia, Norway, Russia and USA and spent 7 days and 6 nights for the tour. Next exploration trips will be arranged.