The Phong Nha-Ke Bang National Park, inscribed on the World Heritage List in 2003, covered 85,754 hectares. With this extension, the site covers a total surface area of 123,326 hectares (a 46 % increase) and shares a boundary with the Hin Namno Nature Reserve in the Peoples Democratic Republic of Laos. The Park`s landscape is formed by limestone plateaux and tropical forests. It features great geological diversity and offers spectacular phenomena, including a large number of caves and underground rivers. The site harbours a high level of biodiversity and many endemic species. The extension ensures a more coherent ecosystem while providing additional protection to the catchment areas that are of vital importance for the integrity of limestone landscapes.