Located in the Quang Binh province, the Son Doong Cave is now known as the world's largest cave.

Discovered by a local named Ho Khanh in 1991, its biggest section is more than 200 meters wide, 150 meters high, and at least 6.5 kilometers long, though the explorers said they were unable to explore it fully. After British explorers searched the area April 10-14, 2009, they concluded that it is much larger than the previously known biggest cave.

Because of the growing interest shown by the public and the media in the ongoing exploration of Hang Son Doong Cave, the cave will officially open to tourists next year.Its size is indeed so large that the end is yet to be found. Howard Limbirt, an expert from the British Cave Research Association, however recommended that due to unexplored nature of cave, trial routes through the cave are to be tested before official tours will be launched next year.

He also added that to ensure the safety of the tourists, authorities and travel companies should protect the primary site and the surrounding ecological environment. Exploration of the cave is preferential in dry season, between February and August.The trial tours will be offered twice a month and limited to a small group of seven or eight visitors.