In Son Doong (Photo: Oxalis Adventures-Ryandeboodt)

Son Doong is the only Southeast Asian representative on the list of record-breaking nature wonders, which also includes the Angel Falls in Venezuela, the world’s tallest waterfall; the world’s longest Nile River in Africa; Mount Kilauea, the world's most active volcanic mass in the US, and Mount Everest, the world’s highest mountain.

Son Doong is estimated to be between 400 and 450 million years old, but it was only "discovered" in 2009. The cave, which has a total length of 9 km, opened to tourists in 2013, four years after members of the British Cave Research Association finished their exploration.

"It is large enough to have a weather system independent from the outside world. The cave even has its own clouds, jungles, and rivers, and appears almost like a fantasy world untouched by humans," the Insider said.

Tours of Son Doong have resumed since mid-May after being closed for over two months due to the impacts of the COVID-19 pandemic.

Source: VNA