Women stand on the “martyrs' bridge” spanning the Tigris River in Baghdad, Iraq, Friday, February 24, 2023. (Photo by Jerome Delay/AP Photo)

Cars slowly move along a bridge in traffic jam in central Moscow, Russia on December 11, 2018. (Photo by Yuri Kadobnov/AFP Photo)

A motorway bridge crosses the icy Hunhe River in Shenyang, China on December 12, 2019. (Photo by Costfoto/Barcroft Media)

“Kids of Sapa”. Four little beautiful Hmong girls from Lao Chai Village, near Sapa, Vietnam. (Photo and caption by Felipe Hanower/National Geographic Traveler Photo Contest)

An Iraqi army cadet participates in “the leap of faith”, from a bridge as part of their training, in Baghdad, Iraq on December 15, 2023. (Photo by Ahmed Saad/Reuters)

A full moon rising over the Re Island Bridge in Rivedoux, France is pictured on December 14, 2016. (Photo by Xavier Leoty/AFP Photo)

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.

Runner-up; Hon Yen marine ecosystem. Phu Yen, Vietnam. Every year between May and August, the coral of this rich and diverse ecosystem becomes exposed at low tide. (Photo by Truong Hoai Vu/Royal Society of Biology Photography Competition)