VietNamNet Bridge – Hoang Huong Giang explored the notoriously challenging Tu Lan Cave System – a maze of dark caverns, winding rivers and rock formations that hasn't yet been fully discovered.

Teamwork: A group of young professionals took on the Tu Lan Cave System. They came out feeling strong and accomplished. — Photos courtesy of Mekong Capital

This summer everyone is talking about Son Doong, the largest cave passage by volume in central Viet Nam's Phong Nha - Ke Bang National Park. Its reputation is well deserved: One chamber is five kilometres long, another 182 metres high.

Officially discovered by Ho Khanh, a local farmer, in 2001, the massive cave system only gained international fame when a group of scientists from the British Cave Research Association, led by Howard Limbert conducted a survey in Phong Nha – Ke Bang in 2009.

Governed by strict eco-friendly requirements, small trekking groups are allowed to explore the natural wonders of the region with the help of guides and porters, who ensure there is a minimum of disturbance to the environment and nothing is left behind.

Light at the end of the tunnel: Explorers say they found swimming in the rivers fascinating under thousands of hanging bats.

We as a group were eager to take on the mammoth challenge of exploring the Son Doong Cave, but after considering our team's health condition, we opted to explore Tu Lan Cave System some 70km from Phong Nha – Ke Bang Park over four days and three nights.

Smaller than Son Doong Cave it may be, but Tu Lan Caves, which were only officially discovered in 2009, is no less magnificent. Unbelievably, it has yet to be fully explored – even the guides have not ventured into all its caves.

Our group of 19 consisted of young professionals, ranging in age from late 20s to 40. Despite being office-bound, we are all fairly active, working out, running and swimming. Fitness is a must, as we were to find out. The word "trekking" is also a misnomer: the trip involved cave swimming, rock climbing, abseiling and bouldering (climbing over large boulders).

Although we are fit and know each other well – we climbed Mount Kinabalu in East Malaysia a few years back – exploring Tu Lan would present its own difficulties, so we honed our team spirit. Together, we overcame all the challenges, achieved a lot of breakthroughs, spent time outdoors and engaged with natural environments.

For me, my greatest fear was swimming in the complete dark - something that is unavoidable when navigating Tu Lan Caves. I was haunted by the fear I would be lost forever in the unchartered rivers coursing through the caves. But my fears were unfounded and when it actually came to swimming in the cave system, I was entranced by the experience. In fact, swimming in the shimmering emerald green water of the caves and watching the mineral-laden stalactites overhead glitter in the shafts of sunlight penetrating the roof of the cave, proved to be my most memorable experience of the whole trip.

That doesn't of course diminish from the euphoria of trekking through forests of wild orange trees (whose fruit littered the ground) and fields of grass that were home to thousands of butterflies of every size, shape and colour. It was like walking into a magic land, something we would only see in fantasy movie or read about in a children's fairy tale book.

Everyday we would trek and climb and swim. Nothing in our path proved too big an obstacle to negotiate – we just kept on going from point A to B, all the while, mesmerised by our beautiful surroundings.

One of my companions, Do Thi Khanh Van, 34, later wrote on her Facebook: "Exploring the caves was extremely nerve-wracking but exciting, including climbing down a 20m ladder, walking along a very narrow cliff above a dark deep river, swimming in the total darkness under hundreds of bats."

During our trek, we actually spent three nights in Tu Lan, which in itself was an incredible experience, to say nothing of waking up in the morning to find our porters preparing breakfast.

Filling the void: Hoang Huong Giang says she misses the jungle and would definitely come back.

We were advised to carry with us a minimum of clothing to keep the weight of our packs down. A change of clothing during the day is out of question. Our clothes went from wet to dry to wet again several times a day. But at the end of each day, we spent a blissful night at our campsite, where we slept off the rigours of the day and awoke in the morning thoroughly refreshed.

Exploring Tu Lan challenged us at every step, and the level of difficulty rose day after day, but in the end, our hard work paid off and we were rewarded with memories that will remain with us for the rest of our lives. And I for one am now a firm believer in the popular saying: "No pain, no gain!"

Leave nothing

Although exploring Tu Lan Caves and the other cave systems in Phong Nha-Ke Bang National Park might sound daunting, you will be thoroughly looked after by your guides and porters. We were also lucky to meet Ho Khanh and Howard Limbert, who briefed us on safety and the importance of respecting the environment.

Trekkers: Every day they walked long distances, swam across rivers and climbed mountains amid beautiful scenery.

As for our guides and porters, it seemed they could not do enough for us. One day after we had erected our tents, it started to rain and all the guides and porters built small dykes with their hands to divert the water away from our tents. They were always cheerful and clearly loved their work and their beautiful surroundings, which they doted on as much as us – every now and again a porter or guide would pick up a piece of litter someone had carelessly discarded. For this, if not their attentiveness to our every needs, I take off my hat to them.

Making the most of it: The group spent a night camping near a waterfall.

Back in my everyday world, I still relive my trip to Tu Lan. In my mind's eye, I see the thousands of stars overhead under which we camped, a subterranean waterfall spewing out torrents of white water. I see the full moon rising over mountains, shedding magical light over the valley where we camped for a night.

The only cloud on the horizon when I think about Tu Lan and Phong Nha – Ke Bang National Park is the proposal to build a cable car to ferry tourists to Son Doong Cave.

Stream of consciousness: The rivers seemed never-ending. They ran under the mountains, behind big bushes and straight into a large cave full of stalactites and stalacmites, stone straws and pearls.

Hopefully, rumours that the project has been scrapped following a public outcry are true because it would destroy virgin forest and scar the landscape. It would also take away the joy of exploration – I'm a firm believer in the adage that it is not arriving at your destination that counts, but the getting there. I'm also reassured by the attentiveness of the local guides and porters, who clearly have a deep respect for their environment.

But mostly, when I think of Tu Lan, I'm filled with a deep longing to return. I miss the forests and the mountains, the rivers and the moonlight, but above all, I miss the thrill of adventure.

VNS