Authorities in Central Quang Binh province will officially open the world's biggest cave, Son Doong, for tourism by January, 2015. This follows a successful pilot programme this year.

Adventure tours to Son Doong will most likely run from January to August. However, they will cease for the rest of the year to avoid flooding.

To protect the delicate cave system, a maximum of 450 visitors will be allowed in each year, almost twice as many as the eight month pilot period.

The pilot programme, organised by Phong Nha - Ke Bang National Park and Oxalis Adventure Tours, had 243 visitors.

The 2015 programme will offer six-day and five-night tours and four-day and three-night tours at cost of 3,000 USD per head. Each month, only eight groups will be allowed to tour.

Son Doong is more than 200m wide, 150m high, and about 9km long. It also houses a jungle and a river, and could fit a 40-storey skyscraper within its walls. The cave was classified as the largest cave in the world by the British Cave Research Association.

It has been recently suggested by the American news website as one of the places to visit. Son Doong was also listed in the "52 Places to Go in 2014" by The New York Times Travel.

Located approximately 500km south of Hanoi, Phong Nha-Ke Bang National Park is a famous destination in central Vietnam and was recognised by UNESCO as a World Natural Heritage Site.-VNA