Two lakes of "great mystery" are located about 500 meters from each other in the Phong Nha Cave. Experts could not reach the bottom of the lakes, although they used modern diving equipment and wires to measure their depth.

The first image of the Xuyen Son Ho bottomless lake.

Director of the Center for Phong Nha - Ke Bang Ecotourism and Culture, Quang Binh province, said the center’s survey team and cave experts have discovered two lakes on the tourist route "Phong Nha Cave - discovering 1,500 meters of mystery." .

The first lake is about 70 m2 and the remaining lake is more than 300 m2. The lake is calm as a mirror. The water is cool and blue. Surveying the first lake, experts were surprised because the lake seems to have no bottom.

Experts could not reach the bottom of the lake, although they used modern diving equipment and wires to measure the bottom. As usual, the survey team decided to name the first lake Xuyen Son Ho.

This is the second discovery in a short period of time after the color-changing stalactite in July, once again it is confirmed that Phong Nha Cave is the top cave with seven outstanding criteria: the cave with the tallest and widest entrance, cave with the most beautiful sandy ground and reef, cave having the most beautiful underground river, cave with the the most magical and magnificent stalactites, cave with high and wide caves, cave with deep and beautiful underground lakes and cave with the longest water cave.

On October 1, the Centre for Phong Nha - Ke Bang Ecological and Cultural Tourism launched the tour to Xueyn Son Ho Lake and held a contest to name the lake of more than 300m2.