New discoveries in underground river inside Son Doong announced

The remark was made by Vice Chairman of the provincial People's Committee Tran Tien Dung, at an international press conference about the diving expedition in the underground river inside Son Doong Cave, in Ha Noi on April 9.

The diving expedition opened a new page of exploration about the underground cave system located at a depth of over 90m and created a new page for cave experts to explore more about the underground caves. In the meantime, Phong Nha - Ke Bang is still a mystery to explorers, researchers and scientists, he added.

According to CEO of Oxalis Company Limited Nguyen Chau A, for over 30 years, the British Cave Research Association (BCRA) has been conducting multiple cave explorations, surveys and researches to study the numerous cave systems present in Quang Binh Province of Vietnam. Inviting the best cave diving experts in the world to dive in the underground river of Son Doong Cave, opens great opportunities to reveal the hidden secrets deep within the underground caves that the cave experts and researches could never explore before.

On this expedition, the cave experts found a new tunnel system at a depth of 60m,
the deeper it goes the wider the underground cave system opens up.
The depth of Son Doong has increased to over 500m in
total from the entrance to the final passage yet to be explored.

Oxalis Company Limited and the BCRA have collaborated with the Phong Nha - Ke Bang National Park Management Board to invite the cave diving experts to join in the exclusive expedition. All the invitees belong to the top five cave diving experts in the world. The diving exploration team includes: Team Leader: Martin Holroyd - BCRA specialist, three members who have contributed to the rescue of the Wild Boar football team in Tham Luang, Chiang Rai, Thailand in 2018, including Rick Stanton, Jason Mallinson and Chris Jewell. The team l was also accompanied by Laura Jewell, the diving equipment coordinator for the expedition.

According to Howard Limbert, who is an expert of the British Royal Caving Research Association, the purpose of the diving expedition of the cave experts is to find out the connection between Son Doong Cave and Hang Thung Cave which are 600m apart. With the initial assumption that when reaching a depth of 25m, the underground river section inside Son Doong Cave will run horizontally to connect to the underground river inside Hang Thung. However, in fact, when the expert team measured the depth of the underground river by ropes, the bottom of the Son Doong underground river is located at a depth of 93m. At this depth, it is impossible to use ordinary compressed air and the divers need to find another ceiling spot with the depth of 40 to 50 meters, to use the ordinary compressed air together with the rebreather system to be underwater for longer hours.

Accordingly, diving expert Jason Mallinson, conducted a dive to the depth of 77 metres to find the passage to Hang Thung Cave, but he didn't succeed and the depth of the cave is still extended. The diving team has a plan to use helium compressed air to dive deeper to 120 metres and then to 200 metres.

On this expedition, the cave experts found a new tunnel system at a depth of 60 metres, the deeper it goes the wider the underground cave system opens up. The depth of Son Doong has increased to over 500 metres in total from the entrance to the final passage yet to be explored.

In addition to the underground river inside Son Doong Cave, the information from the dive experts shows three distinct levels of development in Son Doong Cave, the high dry level and the underground river level. The divers’ information reveals another level, a deep submerged passage at 93m deep which is actually below 6.

According to cave diving expert Jason, his team will return to Son Doong Cave in the near future to further explore the mystery of the world’s largest cave with better diving equipment, which will allow them to dive to greater depths.