The Phong Nha - Ke Bang Park of Central Vietnam, Quang Nam Province is an UNESCO-recognized World Heritage Site. It gained its recognition in 2003 through the explorations of the British Cave Research Association. The cave system of the park includes Khe Ry, the world’s longest cave with a stream, and the world’s largest cave, Son Doong.
But aside from its cultural significance, the park lately has been the target of mysterious discovery as well as a team of explorers found two lakes so deep that even high-technology equipment could not fathom the depth.
Both lakes are about 500 meters apart from each other inside the park. The surface of one lake is around 70 square meters while the other is over 300 square meters.  Since the bottoms of the lakes could not be measured by modern diving tools and ropes, the depths are only estimated to be more than 1,500 meters deep.
Since the mystery is naturally attracting people to the park, the Phong Nha – Ke Bang Tourism Center started allowing visitors to see the lakes. Moreover, it has organized a competition to name the larger one. The small lake has already been named, “Xuyen Son Ho,” by the explorers who found them, which means “lake that goes through mountains.”