(Son Doong Symphony), a new documentary, will air on Viet Nam Television's channel 1 on February 14 as part of a monthly programme called VTV Special, which has been carried out with the assistance of the Japan International Co-operation Agency (JICA) and Japan's national public broadcasting organisation, NHK.

Ban Hoa Tau Son Doong

The biggest cave in the world - Son Doong, in the central province of Quang Binh - is featured in the second episode.

Hoang Lam, who made the documentary, has explored the cave twice. He spoke about this latest project – his craziest yet, he said.

You have spent ten years making documentaries on different themes. Is this the most challenging project you've worked on? Do you think it might be too adventurous or risky?

Making a documentary on Son Doong Cave is very risky, because natural conditions such as light in the cave don't meet professional demands for shooting.

Before making this documentary, we made other documentary on Tu Lan Cave, which is in the province's Phong Nha-Ke Bang National Park.

Tu Lan Cave also had rough terrain, making it hard to shoot. We had to walk, climb, traverse mountains and dive to shoot. However, light in Tu Lan Cave is OK for shooting.

But there is no light in Son Doong Cave. Moreover, misty clouds envelop the whole scene. Thus, light was our first obstacle.

Documentaries on National Geography, Discovery, TV5 or DW are shot with photosensitive cameras. Viet Nam Television doesn't possess this sort of equipment yet.

Could you tell us more about making a documentary on Son Doong Cave?

The Son Doong tour attracts foreigners. We had two trips to the cave. We were eighth Vietnamese team exploring the cave. The cave tour itself is strictly limited to 30 tourists, but our crew has 86 members.

This number comprises 64 equipment porters, 13 film crew members, four foreign experts and five Vietnamese tour guides.

It was very complicated to keep that many people and our one tonne of equipment safe. Luckily, we had support from our partner, Oxalis Adventurous Tours and Ho Khanh, the local man who discovered Son Doong Cave.

Normally the company provides five-day tours. But we shot for 10 days in the cave.

We moved and worked in darkness, with the only light coming from caving headlights. We had to move with our hands and legs in the four-kilometre cave because there was no road in there. The cave experts forbid us from doing anything that would impact the enormous stalagmites and statuesque stalactites.

The name Son Doong Symphony is beautiful. Is any orchestral music featured in the documentary?

Yes, there is a 70-member orchestra appearing in the documentary. We could not bring the orchestra to play music in the cave - it's impossible. But music helps illustrate the story in the film.

The documentary will feature magnificent scenes from inside the cave, and walls that still bear traces of ancient drawings of animals, plants and people. These artists are the ones who discovered the caves and started protecting them long ago.

What message will the documentary convey?

Simply, that we should acknowledge the value of the enormous natural world and behave kindly towards our natural heritage. — VNS