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./.VNA

Quang Binh to slash entrance fees to caves

Quang Binh to slash entrance fees to caves

Visitors to Quang Binh Province will enjoy a 50% discount on tours to some famous caves in the area.  

The experience of being 7km deep in Paradise cave

The experience of being 7km deep in Paradise cave

Most visitors who have been to Paradise cave, located in Phong Nha Ke Bang National Park, are only allowed to explore just the first 1km into this cave along a wooden staircase and boardwalk under bright lights.