SHINING LIGHT: Nguyễn Văn Úy and his team discovered a brand lake suspended above an underground river when on a safety check of his route.

On May 12, Jungle Boss Tours, an adventure tourism company, announced they had found a new lake inside Thung Cave at Phong Nha Kẻ Bàng National Park. The company had just opened new travel routes to explore Hung Thoòng and received a licence to start taking tourists from January 1, 2023. Hung Thoòng, which encompasses Thung Cave, is a less explored system of caves, located close to the core zone under strict protection of the park. The team that found the lake was led by Nguyễn văn Úy. Here he explains how his team discovered the lake.

Inner Sanctum: Could you tell us about the purpose of your last trip and how you found the lake?

Our team of five went on the last trip. The purpose was to do a regular check on the safety system and check on the level of the underground river in Thung Cave this summer, as this year the drought came quite early.

On our previous trips, we already saw a small path ahead, but the underground river runs very close to the collapse and the temperature drop had caused a thick layer of fog and water steam that partly blocked our view. We decided to start earlier than usual because in the wee hours of the morning, the temperature gap is quite low. Thus it was less foggy and we could see more clearly.

When we got to the collapse, we saw a little path on the cliff between the cave ceiling and the river started to appear. This path is about 40m long and the width only 50cm, with the widest point only 1.2m. We decided to drill at certain points so we could hook on the safety rope to get to the other side of the cliff.

Inner Sanctum: Can you recall your emotions when you saw the lake, and how long you stayed there?

The moment I got to the other side of the cliff, I uttered an excitement scream when I saw the spectacular emerald lake, but I could not fathom its bed. Then we all put on life jackets to swim across it.

When we got to the other side of the lake, I found myself even more surprised. When I looked down, I saw the underground river I used to swim along on my previous trips. But this lake was located on a separate level, not connected to the underground river at all.

The lake is about 15m long, and between 3-5m wide. During this season, its depth is about 3m. From what I understand, this is a calcium lake created from water drops from the cave ceiling; the water temperature was between 18-20 degrees Celsius.

After we checked on the lake, we started taking pictures for filing and spent about 2 hours doing so.

I named the calcium lake, Hồ Lơ Lửng (Floating or Suspended Lake), and the path Hẻm Lừng Chừng (Halfway Path).

Inner Sanctum: How long have you been doing this job?

I am a local. I come from here, so I've been to many cave entrances in our forest trekking trips since I was 12. In 2004, I got to work on several exploration trips with the British Royal Cave Society and have been fascinated by the caves ever since.

I've been working in adventure tourism for 11 years. I have two reasons to continue working and keeping this passion. First, I am keen to discover new destinations. Second, I wish to share and bring this wonderful experience and nature's beauty to domestic and international visitors.

I did not go to college or get officially trained in geology. I listened to cave experts, and read books on the internet, and learnt on the job from my own experience.

GOING DEEP: The discovery of this new lake shall need further study by geologists and cave experts. Photos courtesy of the Jungle Boss team

Inner Sanctum: How can one be well-prepared to go on an exploration trip?

It takes a few things to take part in an exploration. First, you need to maintain good health, then you need to get to know the area, and understand the regional climate during the time of exploration. Second, you have to learn or accumulate some basic survival skills. Third, you must train how to use professional gear as well as first aid and basic rescue skills. If you want to be part of our team, after having learned the above skills, it will take you at least two years.

And if you want to be a visitor, you have to check on our level of difficulty. We ranked them all on our website. For the Hung Thoòng exploration tour that we started in January 2023, it's ranked at the fifth level, which is difficult and only one step below the hardest of our six levels.

The Hung Thoòng adventurous tour lasts for three-day, and two nights, requiring trekkers to have previous trekking experience and no cardio- or heart-related diseases. Before taking the trip, we advise trekkers to maintain good health and to exercise regularly for at least two weeks before the planned trip.

Inner Sanctum: When do you think people will be able to go on this new lake trip?

After we secure a safety system, as we have been planning to add on this new path and trekkers can try this trip some time this year at the earliest. VNS