Bai Tu Long National Park

The boat has only just pulled away from Ao Tiên port. Its engine hums steadily, and a wide sea wind sweeps across the deck. Behind, the shore grows smaller. Ahead, one rocky island after another rises from the jade-green water. This is Bái Tử Long Bay, right beside Ha Long Bay. These are the waters of Vân Đồn, in Quảng Ninh province.

The name has a story of its own. Old tales say that Bái Tử Long is the place where the young dragon bowed down in homage. It is only a legend. But as the rows of islands rise and fall among the waves, like the curving back of a dragon, it is easy to believe.

This trip heads for a very unusual park. It does not sit neatly on one patch of land. Instead it spreads across more than 80 islands, grouped into three clusters. The first two are Ba Mùn and Trà Ngọ. The third is Sậu. This is Bái Tử Long National Park, founded on June 1, 2001. The whole park covers 15,783 hectares. More than a third of it is forest on the islands. The rest is open sea and sheltered coves. It is one of seven national parks in Vietnam that protect both forest and sea.

Some boats turn toward the Cái Đé area, home to Cái Đé Cave. It is one of the largest caves in the Ha Long and Bái Tử Long region, and it runs for several hundred meters. This tunnel cave passes right through the mountain, like a doorway of stone.

Then Trà Ngọ Lớn Island comes into view. In the Cái Lim area of this island hides a small wonder, which people here call tùng áng. Tùng and áng are lakes of seawater tucked inside limestone mountains, held on every side by walls of rock. The sea does not pour straight in. It slips quietly through underground caves and cracks in the stone, then mixes with fresh water running down from the mountain slopes.

That brackish water feeds a mangrove forest of about 10 hectares, called the Hang Dơi mangrove forest. Some of its trees have been alive for several hundred years. True to its name, which means Bat Cave, Hang Dơi shelters thousands of bats. Around it live civets, foxes and monkeys, and in the water there are shrimp, ngán clams and horseshoe crabs. The tùng áng ecosystem of Cái Lim is considered the most distinctive in Southeast Asia.

The boat swings around Trà Thần cove. Beneath the surface lie meadows of seagrass, about 10 hectares in all. They grow at Chương Di and on the Mang River, as well as here in the cove. Seagrass is food for sea turtles. The turtles come here to feed, then set off again on migrations of their own. Deeper down are coral reefs with 106 species of coral. They have been likened to a tropical rainforest on the seabed. The corals release their eggs into the water. Tiny larvae drift away on the currents and seed the reefs of nearby islands.

The park is like a house with six rooms: forest on the earthen hill islands, forest on the limestone mountains, mangroves, coral reefs, seagrass meadows and tùng áng. More than 2,400 species of living things share this house, half of them in the forest and half in the sea. Over 100 of these species are rare. They are listed in the Vietnam Red Book or on the world's Red List.

Farther out lies Ba Mùn Island, the heart of the whole park. The national park was created by enlarging the old Ba Mùn Nature Reserve. The island covers about 1,800 hectares. Among so many limestone islands, Ba Mùn is the only one made of shale, and it still carries primeval forest. No people live there, so the island goes by a very sweet name: Animal Island.

Animal Island has one special resident, the sambar deer. This is the only population of sambar deer in northeastern Vietnam. Across that whole wide region, a single island out in the sea is the one place left where these deer still live in herds.

Every year, hundreds of rare animals are rescued and released back into the wild here, from green turtles and other turtles to Asian black bears, civets and wild cats. When the northeast monsoon blows in, flocks of migrating birds come to the park's islands and waters. Some stay to shelter from the cold. Others only stop to rest their wings.

The forest also holds the Vietnamese slipper orchid, an endemic orchid species. It also has the trai lý tree, a prized hardwood. The park is caring for about 5,000 trai lý seedlings. Three of its trai lý trees have been recognized as Vietnam Heritage Trees. The Biodiversity Museum, founded in 2009, keeps specimens of the finless porpoise.

The waves around here carry history too. In 1149, Emperor Lý Anh Tông ordered the founding of a settlement at Vân Đồn. It became the first trading port of Đại Việt, an old name for Vietnam. The port once welcomed merchant ships from China, Japan and Southeast Asia. In 2023, the Vân Đồn trading port complex was ranked a Special National Monument.

Further back still, in Soi Nhụ Cave, people found traces of prehistoric humans from more than 10,000 years ago. Long before the merchant ships, people took shelter in the caves of this place.

In 2016, this park in the sea was recognized as an ASEAN Heritage Park. The sea turtles, the sambar deer and the flocks of migrating birds have no need to know about that title. To them, this place is simply home.

As evening falls, the boat turns its bow back toward Ao Tiên. From the stern, the whole route lies behind. The tunnel cave, the mangrove forest, the seagrass meadows and Animal Island far off all slip back toward the horizon. The white wake behind the boat stretches out for a while, then fades. And the islands close together again, silent, as if no one had ever passed this way.