2 days: Hoi An - Hue - Phong Nha: world heritage Road

Phong Nha-Kẻ Bàng National Park is a remarkable natural treasure, renowned for housing the largest cave in the world and encompassing over 300 grottoes and caves. Among these, Phong Nha Cave stands out, having been recognized by the British Caving Association as the top cave globally, thanks to its record-breaking features. These include the longest underground river, the highest and longest cave passages, expansive and pristine fine sand beaches within the caves, and some of the most spectacular stalagmites and stalactites formations ever observed. In a significant survey conducted in April 2009, British cave explorers made an extraordinary discovery of 20 new caves stretching across a combined length of 56 kilometers, which also included Thien Duong, the world’s largest cave. This vast karst landscape is not only impressive for its physical scale but also for its geological significance. According to UNESCO’s assessment, the karst formations of Phong Nha-Kẻ Bàng National Park have developed since the Paleozoic era, roughly 400 million years ago, making it the oldest major karst area in Asia. The park provides an invaluable window into Earth's geological history, offering extensive evidence that helps scientists better understand the region's geological, geomorphological, and geo-chronological development. The preservation of this ancient karst system holds great importance for scientific research as well as for the natural heritage of the world.