Vietnam’s Son Doong cave, the largest in the world, could hold a 40-story skyscraper inside. The pristine ecosystem has its own river and jungle. Despite its size, Son Doong wasn’t discovered until 1991. It was lost again for nearly two decades and was fully explored for the first time in 2009. (Photo by Jason Speth/HuffPost)

Thai officials arrive for morning alms as part of celebrations for the 68th birthday of Thai King Maha Vajiralongkorn Bodindrade​bayavarangkun, at Sanam Luang in Bangkok, Thailand, 28 July 2020. (Photo by Diego Azubel/EPA/EFE)

A man takes pictures of the Aurora Australis, also known as the Southern Lights, as it glows on the horizon over waters of Lake Ellesmere on the outskirts of Christchurch on April 24, 2023. (Photo by Sanka Vidanagama/AFP Photo)

Fighting Infections (single image) | Fighting Pandemic by Sudipto Das. “It’s exhausting. A tram conductor in Kolkata, India, wears protective clothing from head to toe even in the heat of a summer afternoon. This was when restrictions were easing after India’s first Covid-19 lockdown – public transport was running, but staff were advised to suit up like this. We’ve all grown used to saluting the efforts of healthcare workers, but plenty of other people in public-facing jobs have performed gruelling duties too to keep people safe”. (Photo by Sudipto Das/Wellcome Photography Prize 2021)

Young children at a Bristol, Great Britain health centre unsure of the benefits of sun-lamps and the special glasses that must be worn, July 1948. The health centre was part of the newly introduced free National Health Service. (Photo by Popperfoto/Getty Images)

Indian commuters wade through floodwaters during the continuous rain shower in Calcutta, India, July 10, 2015. A monsoon shower hit the city and disrupted daily life. The Indian monsoon, takes place between May and September. (Photo by Piyal Adhikary/EPA)

Budgies feed on seeds from a local visitor's hands at Ocean Park in metro Manila, Philippines September 10, 2016. (Photo by Romeo Ranoco/Reuters)

A handout picture provided by the Vatican Media shows Pope Francis holding a flag of Ukraine that was sent to him from the Ukrainian town of Bucha during the weekly general audience in the Paul VI Audience Hall, in Vatican City, 06 April 2022. The pontiff lamented the “massacre of Bucha”, in the Kyiv suburb where dozens of bodies in civilian clothing have been found, and renewed his calls for an end to the war in Ukraine. (Photo by Vatican Media Handout/EPA/EFE)