The website www.placestoseeinyourlifetime.com wrote that Son Doong “is indeed very impressive – there is an entire underworld with the jungle and river, waterfalls, unknown plants and fossils. Cave pearls – calcite crystals – are another unique and interesting feature”.
The cave in the Phong Nha-Ke Bang National Park is followed by the Waitomo Caves in New Zealand and the Melissani Cave in Greece. The list also includes the Batu Caves in Malaysia, Mendenhall Ice Caves in the US, and caves in the Algarve of Portugal.
Son Doong Cave, which scientists believe was formed 2-5 million years ago, was first discovered by a local man in 1991.
It was later made public in 2009 by a group of British scientists from the British Cave Research Association after they extensively surveyed the area.
Son Doong has a length of at least 6.5 kilometres and is estimated to be 200 metres in width and at least 150 metres in height (its largest chamber reaches an incredible 250 metres in height, enough space to accommodate a 40-storey skyscraper.