An Omani woman prepares for a traditional dance during a ceremony attended by Britain's Prince Charles and his wife, Camilla, Duchess of Cornwall in Muscat, Oman, Saturday, November 5, 2016. The royal couple have started a three-nation royal tour of the Gulf in Oman. (Photo by Kamran Jebreili/AP Photo)

In this March 12, 2015 photo, a man tours a graffiti exhibition at the Museum of Modern Art, in Bogota, Colombia. The city-run museum recently held an exhibition highlighting the work of Bogota street artists who go by aliases such as Joems and the MonsTruacioN collective. (Photo by Fernando Vergara/AP Photo)

A pack of wild smooth-coated otters, nicknamed the “Zouk family”, crosses Penang Road in Singapore on March 3, 2021, the World Wildlife Day. The “Zouks”, a well-known otter family in Singapore, started out from the Istana on Wednesday, and made a “royal” tour of various landmarks in Singapore. (Photo by Chine Nouvelle/SIPA Press/Rex Features/Shutterstock)

Jubilee Class steam locomotive 45596 Bahamas crosses the Forth Bridge on its way from Edinburgh Waverley to Aberdeen on a day trip operated by The Railway Touring Company on Wednesday, April 19, 2023. (Photo by Jane Barlow/PA Images via Getty Images)

A tourist's umbrella blows upside down as she covers from the heavy rain and high winds, while she tours the city centre, as storm Konrad hits Spain, Portugal and France, in Ronda, Spain, on March 13, 2025. (Photo by Jon Nazca/Reuters)

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.

An installation of Canadian artists Caitlind Brown and Wayne Garrett is displayed during the Lumina Light Festival in Cascais September 14, 2014. Lumina Light Festival shows artworks of artists from several countries, which are displayed during a tour around Cascais. (Photo by Rafael Marchante/Reuters)

Prince Charles, Prince of Wales (R) and Camilla, Duchess of Cornwall (L) visit Seppeltsfield Winery in Barossa Valley, Australia, 10 November 2015. The royal couple are on a 12-day tour visiting seven regions in New Zealand and three states and one territory in Australia. (Photo by Daniel Kalisz/EPA)