A mysterious lake has been discovered in Thung Cave within the World’s Natural Heritage Phong Nha-Ke Bang National Park, in the central province of Quang Binh, VNA reported.

It was discovered during an expedition by the Junglee Boss adventure tourism company.

After 2 days of going through the forest and zip-lining down the sinkhole of this more than 3km long cave, the group of experts swam through the underground river inside Thung cave of the Hung Thoong system and suddenly discovered a new cave floor, where no human footprint has been set before. This cave floor is extremely unique as it contains a giant emerald green lake located on the main cave branch of Thung cave.

The entrance of the cave. Photo: Le Luu Dung

Photo: Le Luu Dung

The lake is located around one kilometre from the entrance of the cave, in one of the most pristine caverns in the area, situated deep within a strictly protected zone of the national park.

It was found in an area about 15 metres higher than the main underground river branch inside the cave, making it look like it was 'floating' on the cave wall.

The lake is located at a much higher altitude than the normal water level of Thung cave.Photo: Le Luu Dung

The lake is surrounded by stalactite columns with an underground river system underneath it. The newly-discovered lake has a transparent emerald green color.

The source of water flowing into the lake has not yet been determined, with the exploration team also discovering a passage along the cave wall of Thung Cave that traverses the main underground river branch.

Photo: Le Luu Dung

Because there is not enough diving equipment, the survey team has not yet measured the depth of the lake, and has not yet found the source of water flowing into this lake. Due to the lake's unique location, the survey team temporarily named it Lo Lung (Floating) lake.

The trip to explore Thung cave will be conducted before the rainy season to ensure the safety of the group. The exploration team also hopes to find a new cave system inside Thung cave.

Phong Nha-Ke Bang National Park in Quang Binh is one of the most spectacular wilderness sites in South East Asia and one of the 2 largest limestone regions in the world. It was recognized as a World Heritage site for the second time for its ecological system and biodiversity at the 39th session of the World Heritage Committee in Bonn, Germany in 2015. The first time was in 2003 for its geological and geomorphologic values.

It is home of more than magnificent 300 caves and ranks among the most popular tourist destinations in Vietnam, including the world's largest cave, Son Doong; the world's 3rd largest cave, En cave; and the longest dry cave in Asia, Thien Duong (Paradise) Cave.

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