In 2002, a representative of the Thien Ha Cave tourism site said the cave was discovered when locals found a narrow crevice on Tuong Mountain that could fit just one person.

For the next ten years, local residents worked by hand, digging out mud, soil, sand and rocks that filled the passage almost to the ceiling. Their painstaking effort finally cleared the way to the interior.

Today the cave stretches about 700 metres: a 200‑metre dry corridor followed by a 500‑metre water‑filled chamber. Visitors first enjoy a 15‑minute boat ride on the Ben Dang River, then walk roughly one kilometre to the three‑metre‑wide entrance.

At the end of the dry section, a natural skylight—called the “sky gate”—lets beams of sunlight flood the cavern, creating a halo that looks like the Milky Way. Boats then glide through the underground river, surrounded by glittering stalactites.

American experts assess that the stalactite system inside Thien Ha Cave remains “alive” and continues to grow, a rarity among caves in Ninh Binh Province.

The ten‑year transformation turned an almost inaccessible crack into a world‑class attraction, showing how community perseverance can reveal hidden geological wonders and boost local tourism.