Located in the core area of the Trang An Scenic Landscape Complex in Nam Hoa Lu Ward, Thung Nham Ecotourism Zone, around 100km from Hanoi, spans more than 300 hectares.

It features primeval forests, a unique cave system, northern Vietnam’s largest natural bird sanctuary, a year-round flower island and tropical gardens, according to the ecotourism zone’s website.

The Thung Nham Bird Park is home to around 50,000 birds belonging to 46 species, including both migratory and resident birds.

It has breeding groups of storks, night herons, whistling ducks, teals, white-rumped shamas, starlings, and other species.

The area also reports the presence of the great hornbill (Buceros bicornis), a rare species listed in Vietnam’s Red Data Book.

From caves to a sky alive with birds

The best time to visit Thung Nham Bird Park is during the breeding season, which runs from August to April.

During a recent trip to Ninh Binh, the weather was pleasantly cool, making it ideal for photography and birdwatching.

Visitors can reach the bird garden by boat.

When we arrived at Thung Nham Bird Park, it was still early and the birds had not yet returned to their nests, so we took our time exploring But Cave, a natural water cave connecting Nam Hoa Lu and Tay Hoa Lu wards.

To travel through it, we had to take a boat.

The closer the boat drew to the cave entrance, the more clearly I could feel the cool air against my skin.

The darkness inside the cave made my heart race, especially as the ceiling was so low that I could touch it just by reaching up.

The rhythmic splash of the oars mingled with the soft dripping of rainwater that had seeped through cracks in the rock and fallen into the water below.

By the time we returned to the boat landing, it was late afternoon. We rushed to another boarding point to watch the birds return to their nests.

When the boat ventured deeper into the park, the sight grew breathtaking. Flock after flock of birds returned, alighting on the branches and grassy thickets.

Many different types of birds perched near the water, watching the boats pass. They showed no fear of people, as though they were used to visitors arriving every afternoon.

The birds preened and rested in trees dotted with nests. A kingfisher suddenly plunged into the water to catch its prey.

When the boat slowly turned back towards the landing, we still kept looking back, watching the silhouettes of birds wheeling against the fiery red sunset.

Along the Ngo Dong River, through the heart of limestone mountains

The next morning, we took another boat trip to explore our next destination: Tam Coc - Bich Dong tourist area.

Tam Coc means three caves: Ca, Hai and Ba. These caves were formed as the Ngo Dong River carved its way through the limestone mountains.

We noticed that the local boat rowers used their feet to work the oars.

Our boatman explained that this was less tiring, as each round trip covered around ten kilometres.

To take turns carrying passengers, the rowers had to draw numbers and wait for their turn. They earned VND200,000 per trip (US$7.73).

“Sometimes guests leave a little extra as a tip, which always makes my day,” he said.

Even after passing through so many caves by boat, we still felt a strange flutter of excitement each time the sky gradually came into view as we passed through another cave.

The Ngo Dong River was crystal clear. Towering limestone mountains rose on either side, embracing the river.

Water lilies were in full bloom along both banks, their vivid pink flowers brightening the landscape.

Local people gathered them into bunches and sat along the banks, selling them to visitors to pose with for photographs.