The tunnel is far below sea level and is the latest of Sơn Đoòng’s secrets to be uncovered. The discovery was announced following a research diving trip made by a team divers from the British Caving Association. How far have they gone with their expedition?
Beyond the growing primeval forest in the cave and its own climate system, what has not yet been seen in the underground water passage in Soon Doong Cave is still a luring challenge for the world's leading cave scientists.
