The programme will also feature images of Vietnam, including Ha Long Bay and the Son River which meanders in Quang Binh Province.

The programme is scheduled to air at 6:00 - 8:00 pm on May 13 in Vietnamese time; and expected to attract directly 6 millions viewers. Viewers in Vietnam can watch the programme later on website abc.go.com.

The television network will report live from inside one of the world's most beautiful caves in Quang Binh province. The exact location is being kept a secret from the public until filming is finished.

A 32-second trailer of the programme was screened online last week, drawing many viewers.

To prepare for the programme, ABC sent a 12-person crew and more than a tonne of specialised equipment to Vietnam.

Son Doong cave located in Quang Binh Province’s Phong Nha Ke Bang National Park recognized as a world natural heritage site by UNESCO.

The cave was firstly found by a local, Ho Khanh, who discovered Son Doong Cave in 1991 and took the explorers to the site of the cave; and then explored by a team of British cavers. Its largest chamber is more than 5km long, 200 m high and 150m wide.

The world's largest cave has been also listed as one of famous places in the world, which will become “hotspots” for visitors over the next two decades by The Huffington Post. The American Business Insider Magazine has recognized Son Doong cave system in the province as one of the world’s 12 most impressive.

By Nhu Y