Hanoi designer Ha Duy, 33, and his friends began their 10 km journey at Hang En (Swallow Cave) in Quang Binh Province – where many swallows can be found nesting. After a day here, the group exited the cave at the back, crossed a stream and passed a segment of a dense forest – a task made possible thanks to experienced guides that accompanied them.
After nearly a day, the explorers reached the entrance of Son Doong, the world’s largest natural cave, yet to be exploited by excessive tourism.
The most “goosebump-inducing” experience for Duy was when he swung himself down into the cave. “It was too slippery and dangerous,” he said. Duy had to take a good tight grip of the rope and learn to balance his shoulders before slowly sliding down. “The feeling of walking on a steep rock wall with underneath me nothing but darkness was really scary.”