The park was created to protect one of the world's two largest karst regions with 300 caves and grottoes and also protects the ecosystem of limestone forest of the Annamite Range region in North Central Coast of Vietnam.
Phong Nha-Kẻ Bàng is noted for its cave and grotto systems as it is composed of 300 caves and grottos. A 2009 survey brought the total discovered length of the cave system to about 126 km., with many areas still not well explored. The Sơn Đoòng Cave, which was discovered in the 2009 survey by British and Vietnamese explorers, is considered the largest cave in the world. Even before this discovery, Phong Nha held several world cave records, including the longest underground river as well as the largest combined caverns and passageways.
The park derives its name from Phong Nha Cave, containing many fascinating rock formations, and Kẻ Bàng forest. The plateau on which the park is situated is probably one of the finest and most distinctive examples of a complex karst landform in Southeast Asia. This national park was listed in UNESCO's World Heritage Sites in 2003 for its geological values as defined in its criteria viii. In April 2009, the world's largest cave, was re-discovered by a team of British cave explorers of the British Caving Association led by a local farmer named Ho Khanh.
In 1990, for the first time, Hanoi University accepted the cooperation proposal of the British Cave Research Association. They combined efforts in exploring and researching caves and grottoes in the area comprehensively. The first exploration was conducted in 1990 by a group from the British Cave Research Association and Faculty for Geology and Geography of Hanoi University, led by Howard Limbert. They completed research of a large part of Vom Cave.
In 1992, the second exploration was conducted by a group of 12 British scientists, six professors from Hanoi University. This time, this group completed their exploration of 7,729 m of Phong Nha Cave and 13,690 m of Vom Cave and adjacent caves and grottos. In 1994, a third exploration was carried out by a group of 11 British scientists and five Vietnamese professors of Hanoi University. In 1999 scientists from the Vietnam-Russia Tropical Centre also conducted zoological and botanical surveys in the Kẻ Bàng area. Based on the results of these three explorations, more information about the caves and grottoes made available to the Vietnamese and local government for the protection, planning, and tourism development of this park.